BACKGROUND Deep vein thrombosis (DVT) is a common problem in clinical practice causing severe complications. In this retrospective study, the distribution and extent of DVT in the lower limb in symptomatic patients were evaluated. Certain risk factors were also investigated. METHODS The venograms of 187 symptomatic individuals (postoperative, medical, and out-patient) with suspected DVT and symptoms having been present for less than 6 days, were reviewed. Seventy-seven limbs of 76 patients had DVT. Twenty-seven were male (age range 14-82 years, mean 57) and 49 female (age range 12-82, mean 56). RESULTS Age over 40 years and gender (female) were significant predisposing factors, (Z = 4.23, p < 0.001 and Z = 2.19, p < 0.05 respectively). Isolated calf DVT alone was the most common pattern (46%, 36 of 77 limbs), and no difference was seen between postoperative and medical patients (chi 2-test, p = 0.7). Postoperative DVT was found in 29 (38%) limbs. Prophylaxis with LMWH had been given in only 15 of them (52%). No difference was seen in the distribution and extent of thrombosis in relation to the prophylaxis with LMWH (chi 2-test, p = 0.34). CONCLUSIONS Identification of the predisposing factors may enable us to distinguish patients at high risk of developing DVT. The majority of the thrombi commenced in the calf veins and thus meticulous investigation of these veins in symptomatic patients with suspected DVT is necessary.