This study tested the feasibility of using oral ifosfamide to treat bronchogenic carcinoma and compared the pharmacokinetics of intravenous and oral doses of the drug. Patients with advanced bronchogenic carcinoma were evaluated for toxicities associated with oral ifosfamide therapy. Pharmacokinetics for various oral and intravenous doses of ifosfamide were determined by a gas-liquid chromatographic assay of plasma and urine samples. Toxicities associated with oral ifosfamide therapy were minimal. Calculated pharmacokinetics parameters are listed, with the half-lives varying from 0.5 to 4.6 h. Oral ifosfamide therapy was determined to be feasible, and further studies are justified to assess the pharmacokinetics of the optimum dosage and scheduling regimens.