PURPOSE: We examined the association between post-diagnosis statin use (3-hydroxy-3-methylglutaryl-coenzyme A [HMG-CoA] inhibitors) and risk of breast cancer recurrence. MATERIALS AND METHODS: The study included 1945 early stage breast cancer survivors participating in the Life After Cancer Epidemiology (LACE) Study. Women who were diagnosed from 1997 to 2000 and identified from the Kaiser Permanente Northern California (KPNC) Cancer Registry entered the cohort on average 2 years post-diagnosis. Information on statin use was obtained from the KPNC pharmacy database. A total of 210 breast cancer recurrences were reported and verified by medical record review. Cox proportional hazard models were used to estimate rate ratios (RR) and 95% confidence intervals (CI). RESULTS: The mean duration of statin use in the cohort among those who initiated use post-diagnosis was 1.96 years, and lipophilic statins were mainly used (97.8%). Starting statins after diagnosis was suggestive of a decreased risk of breast cancer recurrence (RR = 0.67; 95% CI: 0.39-1.13). Risk of recurrence decreased with increasing duration of statin use after diagnosis (p linear trend = 0.02). CONCLUSION: Our findings provide initial support for an inverse association between post-diagnosis, lipophilic statin use and risk of breast cancer recurrence.