Abstract Many orthopaedic centres screen the proximal leg veins for occult deep venous thrombosis (DVT) in post-operative patients. This paper studies the practical implications of ultrasound screening. Venography and ultrasound with colour Doppler was performed in 51 patients. The time taken and results were recorded. There were seven cases (14%) of proximal DVT. The sensitivity of ultrasound was 86% with a specificity of 100%. There was one false negative (a small, < 1 cm, thrombus of uncertain significance). Both techniques were of similar duration. The results support the use of ultrasound for screening in high risk groups.