Abstract Postoperative hemarthrosis is the most common reported complication after arthroscopic knee surgery. The purpose of this study was to determine the effects of hemovac drainage and tourniquet use on the incidence of postoperative hemarthrosis. Sixty patients who had undergone arthroscopic knee surgery were divided into groups based on tourniquet use and whether a drain was used postoperatively. At follow-up, patients had range of motion recorded, and clinical assessment of their hemarthrosis (Grades 0 through 4). Patients who had a hemovac drain used postoperatively, and those patients who did not have a tourniquet used, had fewer hemarthroses and a greater range of motion at all periods of follow-up. We conclude that use of a drain can decrease the incidence of hemarthrosis and allow patients to regain an active range of motion sooner. Also, the routine use of a tourniquet should be avoided because of its correlation with hemarthrosis.