The bioavailability of fenoprofen from three different fenoprofen calcium capsule formulations containing the equivalent of 60, 165, and 300 mg of fenoprofen was determined in two studies. In the first study, 12 subjects received one capsule of each formulation according to a three-period crossover design. The second study required each of 13 subjects to receive 300 mg of fenoprofen equivalent of the 60- and 300-mg capsules and 330 mg of the 165-mg capsule. The initial study provided information on the linearity of fenoprofen pharmacokinetics, and the second study established that the three capsule formulations were bioequivalent. The bioavailability parameters Cmax, tmax, and AUC0--12 hr for the drug in plasma were consistent with a linear pharmacokinetic model, as were the amounts of fenoprofen and hydroxyfenoprofen excreted in the urine. These data show linearity of kinetics for fenoprofen in plasma throughout the 60--300-mg dosage range after a single dose. Physical measurements of each capsule formulation drug content, weight variation, and dissolution showed the products to be uniform and readily soluble.