The objective of this study was to review our diagnostic approach using color duplex scanning (CDS) in the management of symptomatic outpatients with suspected lower limb deep venous thrombosis (DVT). CDS was carried out in 315 consecutive outpatients with unilateral symptoms consistent with DVT. Both limbs were assessed in 205 patients. Other pathology was routinely sought when the symptomatic limb was free of thrombosis. Acute DVT was present in 25% (76/315) of the symptomatic limbs, and in only 8% it was confined to calf veins. Other pathology was detected in 90 limbs (28%). Swelling with or without pain was associated with DVT in 44% and 10%, respectively. The time elapsed between the onset of symptoms and CDS was 3 days (range 1-6 days). DVT in the contralateral asymptomatic limb was present in 5 (9%) of the 56 patients with DVT in the symptomatic limb. In the absence of DVT in the symptomatic limb, the contralateral asymptomatic limb was free of thrombosis. Clinical diagnosis of DVT in outpatients was unreliable. CDS revealed that only one-fourth of the symptomatic limbs had DVT, and other pathology mimicking DVT was present in 28%. CDS is a useful tool that offers a prompt, efficient diagnosis. Investigation of the contralateral asymptomatic limb seems to be necessary only when DVT is found in the symptomatic limb.