The aim of this study was to determine whether the non-steroidal anti-inflammatory drug, flurbiprofen, which has been shown to be an inhibitor of alveolar bone loss in human periodontal disease, is present in human crevicular fluid (CF) following oral dosing. A method is described whereby routine high-performance liquid chromatography is used to detect the drug in only 20 microliters of CF. 5 volunteers abstained from toothbrushing for 21 days to induce experimental gingivitis and increase the resting flow of CF. 100 mg of flurbiprofen was taken by each volunteer on d 21-28. On d 21 and 28, serum and CF samples were taken prior to dosing and afterwards at 1, 2, 4 and 6 hours. On d 21 the mean peak concentration of the drug in serum was about 11 micrograms/ml and was found between 1-2 h after dosing. The respective values for CF (d 21) were 0.32 micrograms/ml and 4 h. On d 28 flurbiprofen was detected in both fluids prior to dosing. The mean peak concentrations after dosing had increased to 13.13 micrograms/ml (serum) and 0.46 micrograms/ml (CF) although the levels of the drug in CF remained relatively constant throughout the observation period on d 28. The results indicate that flurbiprofen may be detected in human CF after oral administration and that the levels are in excess of the plasma level, which in beagles has been shown to inhibit alveolar bone loss in periodontal disease.