A high-performance thin-layer chromatographic (HPTLC) method for quantitation of ibuprofen from plasma is described. The drug was extracted from acidified plasma with hexane-isopropanol (85:15). The mobile phase composition was n-hexane-ethyl acetate-anhydrous acetic acid (75:25:2). Densitometric analysis of ibuprofen was carried out at 222 nm. The calibration curves of ibuprofen in chloroform and in plasma were linear over the range 2-20 micrograms. The mean values of intercept, slope and correlation coefficient were 0.0422 +/- 0.0018. 1.0356 +/- 0.0213 and 0.9976 +/- 0.0013 for standard curves in chloroform and 0.1044 +/- 0.003, 0.8759 +/- 0.0213 and 0.9939 +/- 0.001 for standard curves in plasma, respectively. The limit of detection of ibuprofen from human plasma (assay sensitivity) was 50 ng and no interference was found from endogenous compounds. The recovery of ibuprofen from human plasma using the described extraction procedure was about 85%. The mean relative standard deviations for within-day and between-day analyses were 2.24 and 2.6% for 5 micrograms and 3.67 and 3.2% for 15 micrograms ibuprofen concentration, respectively. The method was utilized to monitor the plasma concentration of ibuprofen post administration of sustained release capsules in human patient volunteers.