The authors investigate within the framework of a multicentre, randomized and stratified investigation the influence of non-specific BCG immunotherapy in adult patients with Hodgkin's disease. The thus created data base was processed according to the Protocol of a prospective study. Supplementary BCG treatment was compared in a group of 112 patients with the fate of 114 patients in a control group without immunotherapy. Although the mean period of complete remission in the group of vaccinated patients regardless of the clinical stage of the disease was 94 months and in the control group 74 months, the difference was not statistically significant. The five-year survival was 93% in vaccinated patients and 91% in the control group. The probability of 10-year survival does not differ substantially in vaccinated patients (88%) and in non-vaccinated patients (85%). There was no difference in the work capacity of patients in the two groups. Immunotherapy was not selected, when testing prognostic factors by Cox' regression analysis, into any of the prognostically favourable models.