BIS Research, New Products Featured at Annual Meeting of American Society of Anesthesiologists.

NEWTON, Mass. -- -Practice Advisory on Intraoperative Awareness and Brain Function Monitoring Up for Vote by ASA House of Delegates; Aspect management to discuss advisory vote during conference call on October 26 -

The American Society of Anesthesiologists (ASA) Annual Meeting will feature 74 scientific studies related to BIS(TM) monitoring when it convenes on October 22-26, 2005 in Atlanta. At the meeting of more than 5,000 anesthesiologists, Aspect Medical Systems, Inc. (NASDAQ: ASPM) will introduce the BIS VISTA(TM) monitor, the newest addition to the family of BIS monitoring solutions, and launch www.BISeducation.com, a dedicated customer education Web site. The ASA House of Delegates is also scheduled to vote on a practice advisory on intraoperative awareness and brain function monitoring on October 25. After the results of the practice advisory vote are available, Aspect will issue a press release and host a conference call on Wednesday, October 26 at 12 p.m. (EST) to discuss the advisory.

"The ASA annual meeting takes place as the society celebrates its centennial and a century of advocacy and commitment to advancing patient safety. BIS monitoring has a prominent role in research presented at the meeting and we believe that this supports the society's greater commitment to enhance patient care and safety," stated Nassib Chamoun, president and CEO of Aspect Medical Systems. "We are pleased to see growing clinical interest in BIS monitoring and look forward to the vote on the practice advisory by the ASA House of Delegates."

New industry-leading brain monitoring products and education programs

Aspect will introduce the BIS VISTA monitor at the ASA meeting. The new stand-alone monitor offers an enhanced display and user interface as well as greater processing capability, including the ability to support advanced monitoring features. The BIS VISTA monitor runs on the BISx(TM) platform, which was originally introduced to enable BIS technology integration with a wide range of patient monitoring systems sold by leading monitoring manufacturers. The BIS VISTA is expected to be available to customers in early 2006.

"Customer feedback has been instrumental in defining how BIS technology must evolve to address a growing customer base and new clinical environments," Chamoun said. "We have learned that we need to provide customers with a standardized and consistent approach to brain monitoring that meets a wide range of customer needs - whether they utilize integrated or standalone technology, or need a brain monitoring solution in the OR, ICU or procedural setting. The BIS VISTA helps us better address customer requirements, allows for future product development and supports our efforts to further establish BIS monitoring as the product of choice in brain monitoring."

At ASA 2005 Aspect is also launching BISeducation.com, a Web site designed to provide an array of clinical education tools in one easy-to-navigate location. The Web site, which includes reference guides and simulation technology, organizes information into various user levels and specialties to help clinicians tap into the full capabilities of BIS technology.

"BISeducation.com is part of our commitment to provide our customers with educational tools in an effort to promote the safe and effective use of BIS monitoring. These tools are designed to help provide clinicians with information and resources regarding how BIS monitoring can enhance clinical judgment when integrated into clinical practice along with other vital signs and conventional monitoring techniques," said Chamoun.

Conference call details

Aspect will host a conference call and live Webcast about the practice advisory on Wednesday, October 26, 2005 at 12 p.m. Eastern time. Interested parties can dial 1-800-289-0494 (domestic) or 1-913-981-5520 (international). The Webcast can be accessed at www.aspectmedical.com on the Investor page, or at www.earnings.com. Telephone replays will be available by dialing 1-888-203-1112 (domestic), or 1-719-457-0820 (international), access code 9419112. The Webcast replay will be available from October 26, 2005, 3 p.m. EST until November 2, 2005.

About BIS Monitoring

Using a sensor placed on the patient's forehead, BIS monitoring translates information from the electroencephalogram (EEG) into a single number that represents each patient's level of consciousness. This number - the BIS value - ranges from 100 (indicating an awake patient) to zero (indicating the absence of brain activity). Using the BIS value to guide administration of anesthetic medication, in conjunction with other vital signs, allows clinicians to make better-informed decisions to achieve optimal anesthesia.

About Aspect Medical Systems, Inc.

Aspect Medical Systems, Inc. (NASDAQ: ASPM) is a global market leader in brain monitoring technology. To date, the Company's BIS technology has been used to assess more than 12.2 million patients and has been the subject of approximately 2,000 published articles and abstracts. BIS technology is installed in approximately 68 percent of hospitals listed in the July 2005 U.S. News and World Report ranking of America's Best Hospitals and in approximately 40 percent of all domestic operating rooms. In the last twelve months BIS technology was used in approximately 12% of all U.S. surgical procedures requiring general anesthesia or deep sedation. BIS technology is available in more than 160 countries. Aspect Medical Systems has OEM agreements with seven leading manufacturers of patient monitoring systems. The company is also investigating how other methods of analyzing brain waves may aid in the diagnosis and management of neurological diseases, including depression and Alzheimer's disease. For more information, visit Aspect's Web site at http://www.aspectmedical.com.

Safe Harbor Statement

Certain statements in this release are forward-looking and may involve risks and uncertainties. There are a number of important factors that could cause actual results to differ materially from those indicated by these forward-looking statements. For example, the practice advisory on intraoperative awareness may not be approved by the ASA House of Delegates, the Company may not achieve widespread market acceptance of its BIS monitoring technology among members of the ASA who review the final practice advisory statement, and even if approved, there may be no positive effects on the Company's business. The BIS VISTA may not provide the benefits or be available on the schedule currently expected. The Company also faces other barriers to market penetration and acceptance. The Company may not be able to compete with new products or alternative techniques that may be developed by others, including third-party anesthesia monitoring products approved by the FDA, and also faces competitive and regulatory risks relating to its ability to successfully develop and introduce enhancements and new products. Cases of awareness with recall during monitoring with the BIS system and significant product liability claims are among the factors that could limit market acceptance. There are additional factors that could cause the Company's actual results to vary from its forward-looking statements, including without limitation those set forth under the heading "Factors Affecting Future Operating Results" in the Company's Quarterly Report on Form 10-Q for the fiscal quarter ended July 2, 2005, as filed with the Securities and Exchange Commission. In addition, any forward-looking statements represent the Company's views only as of the date of this press release and should not be relied upon as representing the Company's views as of any subsequent date. While the Company may elect to update forward-looking statements in the future, it specifically disclaims any obligation to do so, even if its expectations change. Therefore, you should not rely on these forward-looking statements as representing the Company's views as of any date subsequent to the date of this press release.

BIS, the BIS logo and Bispectral Index are trademarks of Aspect Medical Systems, Inc. and are registered in the USA, EU and other countries. BISx and BIS VISTA are trademarks of Aspect Medical Systems, Inc. All other trademarks, service marks and company names are the property of their respective owners.