OBJECTIVES: Randomized trials have reported that intermittent androgen deprivation therapy (IADT) for advanced prostate cancer improves quality of life more than conventional continuous administration of ADT (CADT) while providing a similar survival benefit. It is unknown whether IADT lowers the risk of ADT-related adverse events than CADT.  METHODS: We conducted a retrospective cohort study of 9,772 advanced prostate cancer patients aged 66 or older, diagnosed during 2002- 2011 who received ADT as primary treatment for their prostate cancer. We identified incidence of serious adverse events, including acute myocardial infarction, stroke, heart failure, type-2-diabetes, and fracture, using inpatient and outpatient claims. We used the cox-proportional hazard model to assess hazard ratios (HRs) of ADT-associated serious adverse events in IADT and CADT users.  RESULTS: The cohort included 5,026 and 4,746 men with metastatic and non-metastatic prostate cancer at diagnosis. A total of 1,709 (17%), 678 (7%), and 945 (10%) men were newly diagnosed with a serious cardiovascular event, diabetes, or fracture, respectively, during the first 5 years after ADT initiation. We did not find differences in risk of other serious cardiovascular events, diabetes, or fracture between IADT and CADT, although we observed a lower risk of heart failure in IADT than CADT in the metastatic group (HR=0.58, 95%C.I. = 0.36-0.92, p=0.02). CONCLUSIONS: This large population-based study showed that compared to CADT, IADT may not alter the risk of serious ADT-associated adverse events in advanced prostate cancer. For elderly men with advanced prostate cancer, physicians should carefully evaluate risks and benefits when initiating ADT and consider IADT to have similar toxicity as CADT, despite its intermittent schedule.