Abstract Background The risk of Cushing syndrome (CS) patients experiencing a thrombotic event (TE) is significantly higher (odds ratio; OR 18%) than that of the general population. However, there are currently no anticoagulation guidelines. Methods A retrospective, single-center, longitudinal study of patients undergoing all types of treatment—surgical (pituitary, unilateral, and bilateral adrenalectomy) and medical treatment—was undertaken. TEs were recorded at any point up until last patient follow-up; myocardial infarction (MI), deep venous thrombosis (DVT), and pulmonary embolism (PE) or stroke. Patients’ doses and complications of anticoagulation were recorded. Results Included were 208 patients; a total of 165 (79.3%) were women, and mean age at presentation was 44 ± 14.7 years. Thirty-nine (18.2%) patients had a TE; extremity DVT (38%), cerebrovascular accident (27%), MI (21%), and PE (14%). Of 56 TEs, 27 (48%) were arterial and 29 (52%) were venous. Patients who underwent bilateral adrenalectomy (BLA) had an odds ratio of 3.74 (95% CI 1.69-8.27) of developing a TE. Of patients with TEs, 40.5% experienced the event within the first 60 days after surgery. Baseline 24-hour urinary free cortisol levels did not differ in patients with or without TE after BLA. Of 197 patients who underwent surgery, 50 (25.38%) received anticoagulation after surgery, with 2% having bleeding complications. Conclusions The risk of TEs in patients with CS was approximately 20%. Many patients had more than 1 event, with higher risk 30 to 60 days postoperatively. The optimal prophylactic anticoagulation duration is unknown, but most likely needs to continue up to 60 days postoperatively, particularly after BLA.