A high performance liquid chromatographic method for the quantitation of celecoxib (CEL) in human plasma is presented. The method is based on liquid-liquid extraction with chloroform and reversed-phase chromatography using a Nucleosil CN column (250 mm x 4.6 mm i.d., 5 microm particle size) and UV spectrophotometer detection at 260 nm. The mobile phase consists of acetonitrile:water (60:40 (v/v)). Flutamide was used as internal standard (IS). The assay was linear in the concentration range of 10-1000 ng/ml when 0.5 ml aliquots of plasma were extracted. Within-day and between-day precision expressed by relative standard deviation is less than 4% and inaccuracy does not exceed 3%. The assay was used to analyze samples collected during human clinical studies.