34 patients with disseminated malignant melanoma (stage III) were randomized to the following therapy groups: Chemotherapy (MeCCNU, NSC 99441; 200 mg/m2, given orally every 8 weeks), or immuno-chemotherapy (1 mg Corynebacterium parvum i.v., on days 1-4 + MeCCNU 200 mg/m2 on day 8, repeated every 7 weeks). Total therapy response rate was 33%; total and partial remissions were achieved in 26% of the patients receiving chemotherapy, and in 40% under immuno-chemotherapy. Interim life table analysis shows that in the group receiving C. parvum + MeCCNU 50% of the patients survived more than 12 months, whereas in the group with MeCCNU survival of 50% was 6 months. Pretreatment with C. parvum did not only potentiate the therapeutic effect, but also reduce the myelosuppression of MeCCNU.