The expression of p53 and mdm-2 proteins was analysed in parrafin sections from 39 cases of Hodgkin's disease (HD) and compared to the presence of Epstein-Barr Virus (EBV). P53 protein was found in Hodgkin and Reed-Sternberg (HRS) cells in 12/39 cases. Mdm-2 protein was found in HRS cells in 10/39 cases. EBV-encoded EBER1-2 mRNAs and LMP-1 protein expression were found in HRS cells in 16/39 cases. In view of the LMP-1 oncogenic potential in vitro, these findings suggest that EBV may be involved in the pathogenesis of a proportion of HD cases. The coexpression of mdm-2 and p53 proteins was found in HRS cells in 10 cases, whereas in 27 cases neither was identified and in 2 cases there was no coexpression of mdm-2/p53. The simultaneous p53/mdm-2 protein expression, in view of previous findings which showed that most cases of HD display no p53 gene mutations, suggests that mdm-2 protein expression may be one of the factors responsible for the stabilisation of p53 protein in these cases. This could be important, in the pathogenesis of these cases of HD, since mdm-2 may deregulate the p53 dependent growth suppressive pathway. Mdm-2-/ p53+ protein expression may reflect the stabilisation of p53 protein by proteins other than mdm-2, mutations in the p53 gene making it unable to activate mdm-2, or the deregulation of the mdm-2 gene. No relationship was found between the presence of EBV and the expression of p53 and/or mdm-2 proteins.