Serum concentrations of flurbiprofen were measured following single oral doses of 50 mg to 200 mg in patients who previously had received flurbiprofen over long periods of time. The apparent elimination half-lives in groups of patients who received different doses were not significantly different from each other nor from the value previously obtained in a group of healthy volunteers given a single oral dose of 50 mg. Areas under serum concentration versus time curves were linearly related to dose over the range of doses examined. The results indicate that the pharmacokinetics of flurbiprofen are not significantly dose-dependent over the range of doses studied and that administration of relatively high doses of flurbiprofen over long periods of time neither induces nor inhibits flurbiprofen metabolism.