Using 125I-fibrinogen scanning the incidence of post-operative DVT amongst patients with gynaecological malignancy was shown to be 37.9% which is substantially higher than the 10% to 15% expected in a general gynaecological population. Twenty per cent of the total group studied had isotopic evidence of bilateral venous thrombosis post-operatively. The inaccuracy of clinical diagnosis was demonstrated, and also the need to investigate both limbs if thrombosis was suspected. The incidence of post-operative DVT was found to be significantly lower in smokers (11.5%) compared with non-smokers (68.4%) (p less than 0.00025).