Patients with immune thrombocytopenia (ITP) who relapse after an initial trial of corticosteroid treatment present a therapeutic challenge. Current guidelines recommend consideration of splenectomy, despite the known risks associated with surgery and the postsplenectomy state. To better define these risks, we identified a cohort of 9976 patients with ITP, 1762 of whom underwent splenectomy. The cumulative incidence of abdominal venous thromboembolism (AbVTE) was 1.6% compared with 1% in patients who did not undergo splenectomy; venous thromboembolism (VTE) (deep venous thrombosis and pulmonary embolus) after splenectomy was 4.3% compared with 1.7% in patients who did not undergo splenectomy. There was increased risk of AbVTE early (<90 days; hazard ratio [HR] 5.4 [confidence interval (CI), 2.3-12.5]), but not late (≥90 days; HR 1.5 [CI, 0.9-2.6]) after splenectomy. There was increased risk of VTE both early (HR 5.2 [CI, 3.2-8.5]) and late (HR 2.7 [CI, 1.9-3.8]) after splenectomy. The cumulative incidence of sepsis was 11.1% among the ITP patients who underwent splenectomy and 10.1% among the patients who did not. Splenectomy was associated with a higher adjusted risk of sepsis, both early (HR 3.3 [CI, 2.4-4.6]) and late (HR 1.6 or 3.1, depending on comorbidities). We conclude that ITP patients post splenectomy are at increased risk for AbVTE, VTE, and sepsis.