The simultaneous capillary GC determination of underivatized antiandrogen cyproterone acetate (CPA) and its active metabolite 15β-hydroxycyproterone acetate (OH-CPA) in spiked urine was performed on a flexible VCOT quartz capillary column, coated with a non-polar CP-Sil 5 CB liquid phase. A split/splitless injector and a flame-ionization detector were used. Equilin was used as an internal standard, and resolution of all the compounds was achieved in 6 minutes. Limit of detection was 0.04 μg/μl of injected amount for both CPA and OH-CPA, the recoveries were between 91.35% and 105.56%, and the relative standard deviation varied from 3.35% to 7.38%. The method is applicable in analysis of these steroids in biological fluids.