Non-specific immunotherapy with monthly intramuscular injection of Corynebacterium parvum has been investigated by randomized clinical trials in patients with advanced cancer. Thirty-six patients with disseminated melanoma were treated with either imidazole carboxamide (DTIC) alone or DTIC plus C.parvum. A 19% objective response rate was observed. The mean survival time was similar for both groups. Thirty-three patients with disseminated colorectal cancer were treated with either 5-fluorouracil (5FU) alone or 5FU plus C.parvum. No objective responses were observed. The mean survival time was similar for both groups. No advantage has been demonstrated in either tumour group by adding C.parvum to standard chemotherapy.