Approximately 30-50% of cases of ovarian adenocarcinoma harbour mutations in the p53 tumour-suppressor gene associated with elevated levels of the protein detected by immunohistochemical staining. To investigate any relation between the presence of mutant p53 and clinicopathological features of disease, we examined a series of 50 cases of epithelial ovarian adenocarcinoma for expression of p53 by immunohistological staining on fixed, paraffin-embedded tissue sections using the polyclonal antibody CM1, and by direct nucleotide sequencing of polymerase chain reaction-amplified DNA from selected cases. Of the 50 cases examined, 28 (56%) were p53 positive and there was no significant correlation between p53 status and differentiation stage, clinical (FIGO) stage, multidrug resistance (mdr-1 P-glycoprotein) expression or response to treatment. However, we observed a statistically significant difference between the high prevalence of p53-positive serous tumours (18 out of 23) and the lower prevalence of p53-positive cases in mucinous tumours (3 of 12) suggesting that factors related to disease aetiology, associated with these histological subtypes, may determine the prevalence of functional inactivation of the p53 tumour-suppressor gene in ovarian adenocarcinoma.