Summary. Background: Data on clinical outcomes of patients in the general population undergoing knee replacement or hip replacement surgery are sparse. Objectives: To conduct an observational study using insurance claims data to assess the incidence of selected clinical events following knee replacement or hip replacement surgery in the USA. Patients/Methods: A total of 97 469 knee replacement patients and a total of 45 203 hip replacement patients were included during the period 2004–2008; the median age was 64 years, and 63% of knee replacement patients and 55% of hip replacement patients were women. Results: During a median follow-up of 70–71 days, the incidence rates in knee replacement patients and hip replacement patients were, respectively: ischemic stroke, 15 and 19 per 1000 person-years; acute coronary syndrome (ACS), 15 and 18 per 1000 person-years; bleeding events, 46 and 47 per 1000 person-years; venous thromboembolism (VTE), 64 and 45 per 1000 person-years; and hepatic events, one and one per 1000 person-years. Approximately 45% of knee replacement and hip replacement patients had no claims for outpatient anticoagulant therapy within 1 week after discharge from hospital. Conclusions: Ischemic events such as stroke, ACS and VTE are important adverse events following knee replacement and hip replacement surgery. The results reported here can help in making challenging decisions regarding the clinical management of risks attributable to bleeding events and clotting events.