In a crossover study the effectiveness of intermittent maintenance doses of nitrogen mustard was compared to that of vinblastine sulfate in the treatment of 61 patients with advanced Hodgkin's disease. Forty-five of the patients had had previous radiation therapy. Nine of 29 patients who received nitrogen mustard as the first drug had a complete response and five had a partial response. The comparative results in 32 patients receiving vinblastine sulfate first were nine complete responses and 13 partial responses. The median duration of the complete responses to each drug was 43 weeks. The partial responses were of shorter duration. When the second drug was given in adequate doses, almost as many patients responded with a similar median duration of response.It is concluded that nitrogen mustard and vinblastine sulfate are equally effective single agents in the treatment of patients with advanced Hodgkin's disease and that patient preference would favour vinblastine sulfate because of its negligible side effects.