Ten patients with disseminated adenocarcinoma were treated with combination chemotherapy employing Adriamycin and Baker's Antifolate (BAF). There were seven patients with lung adenocarcinoma, two of whom achieved partial remission while the remaining five had their disease stabilized. Drug toxicity to the bone marrow, gastrointestinal mucosa, and skin was dose-limiting and was greater than the known toxicities of the individual drugs. Pharmacological studies of both drugs were performed on five patients to determine whether abnormal pharmacokinetics could explain this collateral toxicity. Adriamycin plasma concentrations and disappearance seemed to be unaffected by BAF. However, BAF levels were prolonged, apparently due to an Adriamycin effect on the plasma elimination of BAF, resulting in a prolonged exposure of sensitive tissues and organs to BAF. Consequently, when BAF and Adriamycin are used in combination, appropriate dose and schedule changes must be made to avoid any potentially serious side effects.