The success rate for injected umbilical vascular occlusion in the published literature exceeds 85 per cent. In this study we assessed the efficacy of two forms of injected sclerosants in achieving umbilical vessel occlusion. 12 cases of attempted ultrasound-guided occlusion over a 2 1/2 year period were reviewed. These were monochorionic (MC) twins (n=6), dichorionic twins (n=3) and singletons (n=3) undergoing fetocide for severe anomalies, or impending fetal demise. Absolute alcohol (n=6), enbucrilate gel (n=5) or both (n=1) were used in an attempt to achieve vascular occlusion. Complete vessel occlusion was achieved in only a third of cases (4/12), three with absolute alcohol and one with enbucrilate gel. In MC twins occlusion was successful in two of six cases. In contrast to previously published data, this large series, containing more cases than the total previously reported, shows considerably poorer success rates for injected umbilical vascular occlusion. Injection of currently available sclerosants can no longer be recommended for umbilical vascular occlusion in human fetuses.