The pharmacokinetics of benoxaprofen in therapeutic doses of 400 or 600 mg as a solution, capsule or tablet were determined in 44 men after single or multiple doses. The plasma levels of the drug after oral administration of a solution best fitted a 2-compartment open pharmacokinetic model, whereas the levels after the solid dosage forms more appropriately fitted the simple 1-compartment open model. The plasma elimination half-life of the drug, when in solid dosage form, was found to be in the range of 19-26 h, justifying once-a-day dosage. Steady state levels of benoxaprofen were obtained after the 5th dose of a 400 mg capsule every 24 h.