Cases of nasopharyngeal carcinoma (NPC) from North Africa show an unusual bimodal age distribution. As elsewhere, the tumor is closely associated with the presence of Epstein-Barr virus (EBV). The expression of EBV genes and c-onc genes was studied in biopsy specimens from tumors at different clinical stages from 11 young (10 to 30-year-old) and 11 adult (30 to 65-year-old) patients. It was found that the two age groups do not differ in their pattern of gene expression, that there is a tendency for later stage biopsies to express more viral and c-onc transcripts, and that samples expressing larger numbers of EBV genes also tend to express many different c-onc specificities.