This study investigates the overall rate of urinary retention in a large cohort of unselected orthopaedic patients who had either general or regional anesthesia and defines the risk factors for postoperative urinary retention in that cohort of patients. A total of 15,681 patients who underwent major orthopaedic surgery with general or spinal/epidural anesthesia were included. Postoperative urinary retention was defined as any patient who required a postoperative consultation to the urologic department regarding voiding difficulty. Age at surgery, sex, type of surgery, medical history including hypertension and diabetes mellitus, and type of anesthesia were analyzed as potential predictor variables. There were 365 postoperative patients who required urology consults for urinary retention (2.3%). Older age at surgery (OR, 1.035; P < 0.0001), male sex (OR, 1.522; P = 0.0004), type of surgery (OR, 1.506; P = 0.0009), history of hypertension (OR, 1.288; P = 0.0436), and history of diabetes mellitus (OR, 2.038; P < 0.0001) were risk factors for urinary retention after orthopaedic surgery. Advanced age, male sex, joint replacement surgery, history of hypertension, and diabetes mellitus significantly increased the risk of urinary retention. In patients with these risk factors, careful postoperative urological management should be performed.