The purpose of this work was to investigate the prevalence, associated features and effect on survival of portal vein thrombosis (PVT) complicating hepatocellular carcinoma (HCC). The autopsy data of a series of 72 consecutive patients (57 male, 15 female) with HCC were reviewed. PVT was found in 32/72 patients (44%), and tended to be more common in female patients (10/15 versus 22/57, P = 0.052). Stratifying the data according to gender, it appeared that the mean age of patients with PVT compared to those without was greater in woman (71.9 +/- 5.9 versus 63.2 +/- 6.9 years, P = 0.024) and younger in men (58.8 +/- 8.9 versus 66.0 +/- 9.9 years, P = 0.007). When PVT was present, it was more likely that a definite diagnosis of HCC had been obtained before autopsy (P = 0.0001) and that death had been caused by bleeding complications (P = 0.007). Median survival times were similar, irrespective of the presence of PVT. During the natural history of HCC, PVT occurs in a substantial proportion of patients. Hormonal factors may have a permissive role in thrombus formation or neoplastic vascular invasion. Although in the presence of PVT a diagnosis of HCC is rarely missed and bleeding complications are likely to occur, patient survival does not seem to be significantly affected.