Four New ZOLL Biphasic Studies Further Demonstrate Superior Clinical Benefit.

CHELMSFORD, Mass. -- ZOLL Medical Corporation (NASDAQ: ZOLL), a manufacturer of non-invasive resuscitation devices and software solutions, announced today that four clinical studies presented at Cardiostim 2004, a major cardiac electrophysiology conference in France, further demonstrate the superior performance of the ZOLL Rectilinear Biphasic(TM) waveform (RBW).

The first was a retrospective study of 1,887 external cardioversion procedures in 1,361 patients, which demonstrated that the ZOLL RBW was shown to successfully cardiovert patients weighing 300 to 430 pounds, with an average energy reserve of 37 joules (J), achieving a 100% success rate. The reserve provides an additional therapeutic margin for patients that are difficult to defibrillate. The study was conducted by Mark J. Niebauer, M.D., Ph.D., Associate Professor of Internal Medicine, and Director of Electrophysiology at the University of Nebraska Medical Center in Omaha.

Three other studies, which further bolster the clinical effectiveness of ZOLL's RBW, include:

--A prospective randomized study showed that the ZOLL RBW provided superior defibrillation performance in a porcine pediatric model, when compared to another commercially available biphasic truncated exponential (BTE) waveform, in terms of energy dose per body weight (RBW 2.2 +/- 1.1 J/Kg, BTE 2.5 +/- 1.3 J/Kg, p = 0.0186) and per heart weight (RBW 3.5 +/- 1.8 J/g, BTE 4.0 +/- 2.0J/g, p = 0.0161). The study was completed by Wanchun Tang, M.D., Vice President of Research Institute for Critical Care Medicine in Palm Springs, Calif.

--A prospective, randomized controlled trial found that RBW defibrillation was superior to monophasic damped sine (MDS) waveform defibrillation for patients initially presenting in a shockable rhythm in an advanced cardiac life support setting. Additionally, shock success for the 200 J ZOLL RBW was superior to the 360 J MDS waveform (53%, 38%, p = 0.015) for defibrillation of all out-of-hospital cardiac arrest patients regardless of the presenting rhythm. The study findings were presented by Laurie Morrison, M.D., of Sunnybrook and Women's College Health Sciences Center and the University of Toronto.

--A study of 28 patients with persistent atrial fibrillation confirmed that internal cardioversion using the ZOLL RBW is feasible and safe, and requires less energy than classic damped sine defibrillation waveforms. The study findings were presented by Georges H. Mairesse, M.D., Department of Cardiology, Cliniques du Sud-Luxembourg in Belgium.

According to Richard A. Packer, President and Chief Executive Officer of ZOLL, "These findings add to the accumulated clinical evidence, which supports the superiority of ZOLL's technology in trials involving more than 8,600 patients. In addition, our M Series(TM) defibrillator, equipped with our biphasic waveform, is the only device cleared by the U.S. Food and Drug Administration to be labeled clinically superior to monophasic defibrillators for conversion of ventricular fibrillation in high-impedance patients, and for cardioversion of all atrial fibrillation patients. Therefore, we believe that our proprietary biphasic waveform offers compelling clinical benefits that provide customers with a strong reason to choose ZOLL's biphasic defibrillators."

About ZOLL Medical Corporation

ZOLL Medical Corporation (NASDAQ: ZOLL) designs, manufactures, markets, and/or sells non-invasive resuscitation devices and software solutions. They include pacing and defibrillation devices (ZOLL's M Series(TM) and AED Plus(TM), and LIFECOR, Inc.'s LifeVest(TM) Wearable Defibrillator); circulatory assist devices (Advanced Circulatory Systems, Inc.'s ResQPOD(TM) Circulatory Enhancer and Revivant Corporation's AutoPulse(TM)); and a fluid resuscitation product called the Power Infuser(R), manufactured by Infusion Dynamics, a division of ZOLL. These devices help healthcare professionals, emergency medical service providers, and first responders diagnose and treat victims of trauma, as well as sudden cardiac arrest.

Additionally, through its subsidiary ZOLL Data Systems, ZOLL designs and markets software that automates the collection and management of both clinical and non-clinical data. With direct operations, international offices, and business partners in all of the world's major markets, ZOLL markets and sells its products in more than 140 countries. For more information, visit www.zoll.com or call [phone].

Certain statements contained in this press release, including statements regarding the anticipated development of the Company's business, our ability to differentiate our products from others on the market, and other statements contained herein regarding matters that are not historical facts, are "forward-looking" statements (as defined in the Private Securities Litigation Reform Act of 1995). Because such statements are subject to risks and uncertainties, actual results may differ materially from those expressed or implied by such forward-looking statements. Factors that could cause actual results to differ materially from those expressed or implied by such forward-looking statements include, but are not limited to, those factors discussed in the section entitled "Risk Factors" in the Company's Quarterly Report on Form 10-Q filed with the SEC on May 19, 2004.

Copyright (C) 2004 ZOLL Medical Corporation. All rights reserved. 269 Mill Road, Chelmsford, MA 01824-4105. AED Plus, M Series, and Rectilinear Biphasic are trademarks of ZOLL Medical Corporation. The LifeVest System is a trademark of LIFECOR, Inc. The ResQPOD is a trademark of Advanced Circulatory Systems, Inc. The AutoPulse Resuscitation System is a trademark of Revivant Corporation. Power Infuser is a registered trademark of Infusion Dynamics, Inc. ZOLL is a registered trademark of ZOLL Medical Corporation. All trademarks are property of their respective owners.