Ras mutations play an important role in many human tumors. They usually occur at only three codons (12, 13 and 61) of the three ras gene family members and lead to altered proteins resulting in a constitutively activated downstream signal cascade. We have examined the N-ras gene status in Hodgkin's disease (HD). Little is known about the pathogenetic events leading to malignant phenotype in HD. Since Hodgkin and Reed-Sternberg (H and RD) cells comprise only a minority of the cellular infiltrate in HD-lymph nodes, molecular studies concerning the status of oncogenes have been difficult to perform and have yielded conflicting results. We have established a single cell PCR assay for N-ras analysis and have examined H and RS cells from 12 cases of HD by PCR amplification and direct sequencing. None of the single H and RS cells examined carried N-ras mutations at either codons 12/13 or 61. Therefore, N-ras mutations are not involved in the pathogenesis of HD.