Many epidemiologic studies, although not all, have shown an inverse relation between non-steroidal anti-inflammatory drug (NSAID) use and risk of incident breast cancer, but the possible influence of NSAID use on breast cancer survival has not been evaluated. We examined the association between self-reported NSAID use and survival after invasive breast cancer diagnosis among 591 postmenopausal women in a prospective study. Cox proportional hazards regression was used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) for breast cancer death as well as all-cause mortality associated with NSAID use. There was an indication of reduced risk of breast cancer mortality and all-cause mortality for women reporting any versus no use of NSAIDs, with multivariate-adjusted HRs of 0.64 (95% CI 0.39–1.05) and 0.57 (95% CI 0.40–0.81), respectively. There was no trend of decreasing risk of death with increasing frequency of NSAID use per week. While the results from this exploratory analysis are preliminary, there is biological plausibility for such an association. Further studies should consider whether NSAIDs, which have biological activity affecting tumor promotion and progression and appear to protect against breast cancer incidence, may be associated with better prognosis after a diagnosis of invasive breast cancer.