Micromuse Announces Launch of Independent User Community.

Business Editors

SAN FRANCISCO--(BUSINESS WIRE)--May 31, 2001

International Netcool(R)Users Group to Foster Open Dialogue;

Provides Forum for Technical Resource Sharing and Customer Feedback

Micromuse Inc. (Nasdaq: MUSE), the leading provider of realtime fault management and service assurance software, today announced the official launch of an independent organization of users and partners of the Netcool(R) software. The International Netcool Users Group (INUG) has formalized its internal bylaws and incorporated in the Commonwealth of Virginia as a 501c not-for-profit organization.

The INUG is chartered to foster an open dialogue within the Netcool software community and to provide a technical forum for sharing network and service management ideas and resources. In addition, the INUG will liase with Micromuse's internal Product Management, Customer Care, and Market Development teams, providing a conduit for communicating Netcool customers' network and service management requests as their needs evolve. The Group also helps in planning programs for the European and North American Netcool User Group meetings. The INUG maintains an informational Website at www.netcoolusers.org.

"Our immediate goal is to expand the representation of the International Netcool Users Group to reflect Micromuse's global customer-base," said Pete Silva, elected the first Chairman of the International Netcool Users Group. "We have launched the organization with a 5-person board of directors, but are prepared to grow. In addition, we have appointed chairs for three committees, including a Membership Committee, a Conference Committee, and a Nominating Committee." Silva is a member of the America Online Network Operations team.

"We are very much looking forward to working with the International Netcool Users Group to help us become even more responsive to our customers' needs," said Lou Steinberg, Micromuse's Senior Vice President, Marketing & Market Development. "A fully independent User Group will provide us with a collaborative forum through which we can effectively add value to our customers' overall Netcool suite experience."

As of March 31st, the international Netcool software community consisted of more than 1,100 customers - including Telco, Internet, Wireless, and Broadband service providers and enterprises worldwide - and more than 200 Netcool suite authorized resellers, systems integrators, and OEMs worldwide.

About Micromuse

Micromuse Inc. (Nasdaq: MUSE) is the leading provider of realtime fault management and service assurance software. Micromuse's recent list of awards include the TeleStrategies OSS Excellence Award for Best New Product for the Netcool(R)/Visionary(TM) application, and Web Hosting Magazine Editor's Choice Award. In addition, Micromuse has been recognized in the Forbes 500, Bloomberg's Top 100 Stocks, the Barron's 500, Deloitte & Touche's Technology Fast 500, San Francisco Chronicle 500, Individual Investor's Index of America's Fastest Growing Companies and Network World's NW200. Micromuse customers include AT&T, BT, Cable & Wireless, Cellular One, Charles Schwab, Deutsche Telekom, Digex, EarthLink, ITC DeltaCom, MCI Worldcom, One2One, Verizon, XO Communications, and a number of financial investment concerns. Headquarters are located at 139 Townsend Street, San Francisco, Calif. 94107; [phone]. The Web site is at www.micromuse.com.

About the INUG

The INUG is chartered to foster an open dialogue within the Netcool software community and to provide a technical forum for sharing network and service management ideas and resources. In addition, the INUG will liase with Micromuse's internal Product Management, Customer Care, and Market Development teams, providing a conduit for communicating Netcool customers' network and service management requests as their needs evolve. The Group also helps in planning programs for the European and North American Netcool(R) User Group meetings. The INUG maintains an informational Website at www.netcoolusers.org.

Netcool and Micromuse are registered trademarks of Micromuse Inc., and used by INUG under license. All other trademarks and registered trademarks in this document are the properties of their respective owners. Any statements contained in this press release that do not describe historical facts may constitute forward-looking statements as that term is defined in the Private Securities Litigation Reform Act of 1995. Any forward-looking statements contained herein are based on current expectations, but are subject to a number of risks and uncertainties.

The factors that could cause actual future results to differ materially from the forward-looking statements include the following: fluctuations in customer demand, the company's ability to manage its growth (including the ability to hire sufficient sales and technical personnel), the risks associated with the expansion of the company's distribution channels, the risk of new product introductions and customer acceptance of new products; the rapid technological change which characterises the company's markets, the risks associated with competition, the risks associated with international sales as the company expands its markets, and the ability of the company to compete successfully in the future, as well as other risks identified in the company's Securities and Exchange Commission Filings, including but not limited to those appearing under the caption "Risk Factors" in the company's most recent Quarterly Reports on Form 10-Q and on Form 10-K on file with the Securities and Exchange Commission and available on the company's web site.