4-Biphenylacetic acid, a potent non-steroidal anti-inflammatory agent forms a solid inclusion complex with beta-cyclodextrin in a 1:1 molar ratio, which exhibits better solubility and dissolution characteristics than the uncomplexed drug. Following oral administration of the complex to rats, quicker and higher drug plasma concentrations can be achieved than with the drug alone. Parallel studies, using the carrageenan paw oedema test, demonstrate a greater anti-inflammatory activity of the complex (ED50 of 2.9 mg kg-1 for the complex and of 6.2 mg kg-1 for the free drug). The complex displayed a better gastric tolerability in the rat than drug alone.