Objective: It has been suggested that both endogenous reproductive hormones and hormone therapy may play a protective role against coronary artery disease (CAD). However, recent clinical trials have failed to demonstrate the benefit of a variety of forms of hormone therapy. The observational data on the role of endogenous reproductive hormones, using surrogate measures such as number of birth, age at menarche, and age at menopause are inconsistent. In addition, the longer-term associations have not been evaluated. The aim of this study was to evaluate the relationships between detailed measurements of endogenous and exogenous estrogen exposure time with angiographic CAD and major adverse cardiovascular events. Methods: We assessed total estrogen exposure time, quantitative CAD by a core angiography laboratory, and prospectively measured major adverse cardiovascular events in 646 postmenopausal women undergoing coronary angiography for evaluation for suspected ischemia in the Women's Ischemia Syndrome Evaluation (WISE) study. Results: Timing of postmenopausal exogenous hormone therapy (HT) use was associated with reduced CAD. Two summarized total estrogen time scores (TET and sTET) were not related to angiographic CAD after accounting for HT use. In addition, these scores were not related to cardiovascular events over a median of 6.0 years of follow-up. Conclusions: There was no independent relation of estrogen exposure time to angiographic CAD or major adverse cardiovascular events in a contemporary cohort of postmenopausal women evaluated for suspected ischemia. Our results suggest that the paradigm of estrogen protection from CAD in women may be more complex than estrogen exposure duration alone. © 2009 Mary Ann Liebert, Inc.