Paroxetine in particular has been speculated to increase the risk of breast cancer. The aim of this study was to determine if breast cancer risk is elevated among women who used paroxetine relative to those who used other antidepressants. We conducted a retrospective cohort study of 109,004 female health plan members who used various antidepressants between 1995 and 2000 to evaluate breast cancer risk. The age-adjusted relative risk comparing ever users of paroxetine to those who used other antidepressants was 1.12 (95% CI 0.96-1.31). Women who used paroxetine 2 or more years did not have a greater risk of breast cancer compared to women who used the medication for a shorter period.