Using duplex ultrasonography, we measured preoperative and postoperative venous flow volume in 32 operated lower limbs without deep vein thrombosis (DVT) after total hip arthroplasty (THA, n = 17) and total knee arthroplasty (TKA, n = 15). We also calculated percentage decrease in mean venous flow volume (MVFV) from before surgery to after surgery. Patients with a history of one of several venous diseases, congestive heart failure, or morbid obesity were excluded. In both groups (THA, TKA), MVFV 3 days after surgery and MVFV 1 week after surgery were significantly lower than preoperative MVFV, but MVFV at 2 or more weeks after surgery did not differ significantly from preoperative MVFV (result 1). Incidentally, the decrease in MVFV in the lower limbs was significantly larger 3 days after TKA than 3 days after THA (result 2). As venous stasis has a central role in thrombus formation, result 1 suggests that the risk for DVT initiation is low at 2 or more weeks after THA and TKA in patients with normal preoperative venous physiologic functions. Result 2 is probably correlated with the evidence that DVT incidence is higher after TKA than after THA.