ROCHESTER, NY — April 5, 2005 — Mpower Holding Corporation (AMEX:MPE), the parent company of Mpower Communications Corp., a leading provider of data and voice services to retail and wholesale business customers, will hold a public conference call to discuss its first quarter 2005 results on Thursday, May 5, 2005 at 10:00 a.m. Eastern. To access the call, dial 1-800-322-0079.

About Mpower Holding Corporation
Mpower Holding Corporation (AMEX:MPE) is the parent company of Mpower Communications, a leading facilities-based broadband communications provider offering a full range of private line, data, telephony, Internet access and Web hosting services for business customers and carriers. Further information about the company can be found at www.mpowercom.com.