There are limited data to suggest that abnormalities of p53 expression may be a late event in the development of adrenocortical tumours. This has been investigated further by examining a series of adrenocortical adenomas and carcinomas by immunohistochemistry for p53 expression and a subset for evidence of mutation in exons 5-8 of the p53 gene using polymerase chain reaction/single strand conformational polymorphism (PCR/SSCP). In carcinomas, the findings have been correlated with survival data and with tumour ploidy. Immunopositivity for p53 was seen in 4 of 34 adenomas and 22 of 42 carcinomas. Mobility shifts were identified in 1 of 4 adenomas and 10 of 21 carcinomas. There was no correlation between immunostaining pattern or PCR/SSCP evidence of mutation and either survival or disease-free survival in carcinoma. There was also no correlation between p53 status and tumour ploidy. While these findings support a role for p53 in tumour progression, abnormal p53 expression does not appear to have any significant prognostic effect in carcinoma.