This study undertaken by the Central Clinical Drug Evaluation Program includes 682 evaluable patients, undergoing 871 courses of imidazole carboxamide with 39 different types of malignant disease. Toxicity consisted of nausea and vomiting for the first few injections, and hematopoietic depression in a relatively small group. A response of 25.1% was noted in 393 patients with melanoma. At the current dosage the drug seems to be well tolerated and is useful in the treatment of metastatic melanoma.