Surgical biopsies obtained from 32 children, and 34 adults with Hodgkin's disease (HD) were investigated for the expression of the EBV encoded Latent Membrane Protein 1 (LMP-1), bcl-2 protein, markers for HD; LeuM1 (CD15), BerH2 (CD30) and the new BLA.36, as well as for B (L26) and T lymphocytes (UCHL1). Before immunostaining, sections were subjected to an Antigen Retrieval (AR) procedure based on microwave irradiation in citrate buffer. In 13 cases staining with and without the AR procedure was compared. Immunoreactivity for LMP-1 was found in 44% of the biopsies from adults and 53% from children. We also found reactivity for the bcl-2 protein in Hodgkin's and Reed Sternberg (HRS) cells in 48% of the biopsies from adults and 45% from children. Immunoreactivity with BLA.36 was found in 94% of the biopsies from adults and 100% from children, with LeuM1 in 83% from adults and 93% from children and with BerH2 in 24% from adults and 84% from children. Nuclear PCNA staining was seen in HRS in all cases both adult and childhood. The T cell marker (UCHL1) displayed no reactivity with HRS cells. In 21% of the adult and 9% cases from the childhood cases we observed reactivity with the B cell marker (L26) in HRS cells. We can conclude that antigen retrieval improves immunostaining results of paraffin sections which were previously negative for bcl-2, LeuM1 and BerH2 antibodies. The high percentage of LMP-1 positive cases, both in adults and in children, indicates that the potential pathogenetic effect of EBV may be of similar importance both in childhood and in adult HD. The new MAb BLA.36 gave consistent immunostaining with HRS cells but also with other cell types. In a panel of markers for HRS cells BLA.36 together with LeuM1 (CD15) and BerH2 (CD30) are useful.