Authors ConTeMpoRARy SuBJeCTDaviD Mirkin is a principal and Catherine Murphy-Barron and kosuke iwasaki are consulting actuaries, Milliman, inc., new york, new york. author CorresponDenCe: David Mirkin, MD, principal, Milliman, inc., one penn plaza, 38th Fl., new york, ny 10119. tel: (646) Fax: (646) 473-3199; e-mail: david.mirkin@milliman.com. Copyright© 2007, academy of Managed Care pharmacy. all rights reserved.BACKGROUND: Endometriosis is a painful, chronic disease affecting 5.5 million women and girls in the United States and Canada and millions more worldwide. The usual age range of women diagnosed with endometriosis is 20 to 45 years. Endometriosis has an estimated prevalence of 10% among women of reproductive age, although estimates of prevalence vary greatly. Endometriosis is the most common gynecological cause of chronic pelvic pain, but published information on its associated medical care costs is scarce.