While many reports describe health-related quality of life (QOL) among breast cancer survivors, few compare QOL before and after diagnosis and whether changes in QOL substantially differ from changes experienced by all women during aging. QOL was examined in a cohort of female residents of Beaver Dam, Wisconsin, aged 43-86 years at the time of a 1988-1990 baseline examination (N = 2,762; 83% of eligible). Participants were re-contacted four times through 2002 to ascertain QOL using the 36-item Short Form Health Survey (SF-36). QOL data for 114 incident breast cancer cases identified by data linkage with the statewide cancer registry were compared with data for 2,527 women without breast cancer. Women with breast cancer averaged 4.5 (95% CI: 1.6, 7.3) points lower than control women on the SF-36 Physical Component Summary (PCS) scale, regardless of time since diagnosis (up to 13 years). Women with breast cancer also reported lower scores on the SF-36 Mental Component Summary (MCS) scale within two years after diagnosis, but not at more distant times. In longitudinal analyses, 26 women who completed the SF-36 before and after breast cancer diagnosis experienced larger declines than age-matched controls in seven of the eight SF-36 health domains (all but role-emotional) and reported relative declines of -7.0 (95% CI: -11.5, -2.6) and -2.9 (95% CI: -6.3, 0.6) on the PCS and MCS scales, respectively. These results suggest that breast cancer survivors experience relative declines in health-related QOL across a broad spectrum of domains, even many years after diagnosis.