Numerous neoplastic states have associated or causal cytogenetic abnormalities. In some cancers, specific chromosomal abnormalities appear to correlate with the clinical characteristics and prognosis. Cytogenetic analysis of Hodgkin's disease is thought to be technically difficult and only a small number of cases with evaluable results have been reported. We have attempted cytogenetic studies of lymph nodes from 37 patients with Hodgkin's disease. In 29 of the 37 patients (78%), successful chromosomal analysis was accomplished. Chromosomal abnormalities were found in 13 patients (45%); five of these patients had been previously treated with chemotherapy. Numerical changes were found in all patients, most commonly involving chromosomes 5, 9, 15, 18, 22, X, and marker chromosomes. Seven patients also had structural abnormalities. The breakpoints 4q32-34, 6q24, 12q13, 12q23-24, and 13p11-13 were each seen in at least two patients. All but two patients had an admixture of normal cells. Three patients had two or more clones, and one had subclones. No statistically significant correlations between chromosomal abnormalities and clinical characteristics were demonstrated, although the number of patients in each subgroup was small. We conclude that chromosomal studies of Hodgkin's disease are likely to be successful. Additional studies are needed to correlate the karyotypical abnormalities in Hodgkin's disease with clinical and biological characteristics.