A rapid and sensitive high-performance liquid chromatographic method for the determination of cyproterone acetate in human plasma has been developed. The chromatographic separation was performed on an analytical mbondapak C8 column (125 yen 4.6 mm, i.d) with an isocratic mobile phase consisting of methanol-water (62.38 v/v). Using ultra violet detection at 282 nm, the detection limit for ... [Show full abstract] cyproterone acetate in plasma was 10 ng/ml. The calibration curve was linear over the concentration range 50-160. 0 ng/ml. Cyproterone was isolated from plasma by liquid-liquid extraction and the recovery was about 90% for plasma. The inter-day and intra-day assay coefficients of variation were found to be less than 10%.