1 Benoxaprofen is a new acidic anti-inflammatory compound which was well absorbed after oral administration to man. 2 Single doses of 100, 200 and 400 mg produced mean peak concentrations in the plasma of 13.0, 33.5 and 45.3 microgram respectively, and the plasma half-life of the compound was between 30 and 35 hours. 3 Multiple dosing with 25 and 50 mg every 24 h achieved an equilibrium conentration in the plasma after 6-8 days, while dosing with 100 mg every 12 h enabled equilibrium to be reached in 3-6 days. Plasma concentrations between 35 and 45 microgram/ml were achieved by giving 100 mg doses every 12 hours. 4 Absorption of benoxaprofen was delayed when the drug was given with food, but the total amount absorbed remained the same. 5 The effect of milling the material to small particle size (19 micron) was to increase the rate of absorption compared to that of unmilled material (58 micron). 6 Benoxaprofen was well tolerated by healthy male subject in the doses given.