Summary. Background: As assessment of clinical pretest probability is the first step in the diagnostic evaluation of deep vein thrombosis (DVT), it is important to know if the clinical features of DVT are the same in men and women. Objectives: To compare the prevalence and clinical characteristics of DVT, and the accuracy of clinical pretest probability assessment, between men and women with suspected DVT. Methods: A retrospective analysis of individual patient data from three prospective studies by our group that evaluated diagnostic tests for a suspected first episode of DVT. Clinical characteristics, clinical pretest probability for DVT, and prevalence and extent of DVT was assessed in a total of 1838 outpatients. Results: The overall prevalence of DVT was higher in men than in women (14.4% vs. 9.4%) (P = 0.001). The prevalence of DVT was higher in men than in women who were categorized as having a clinical pretest probability that was low (6.9% vs. 3.5%; P = 0.025) or moderate (16.9% vs. 8.7%; P = 0.04), but similar in patients in the high category (40.2% vs. 44.0%; P = 0.6). In patients diagnosed with DVT, swelling of the entire leg occurred more often (41.5% vs. 15.7%; P < 0.001), and thrombosis was more extensive (involvement of both popliteal and common femoral veins in 47.9% vs. 21.6%), in women than in men. Conclusions: In outpatients with suspected DVT, the overall prevalence of thrombosis and the prevalence of thrombosis in those with a low or a moderate clinical pretest probability were higher in men than in women.