Comparative pharmacokinetic studies have been carried out with two 20 mg nifedipine active substance-containing retard film coated tablets, Cordaflex produced by EGIS Pharmaceuticals Co., Ltd. and Adalat of Bayer AG. The pharmacokinetic parameters and the relative bioavailability were determined in 15 and 16 healthy male volunteers, respectively after single and repeated administration in open, randomized cross over study. The plasma concentration of nifedipine was determined by HPLC-ED method, using laboratory robot for automated sample preparation. On the basis of graphical and statistical comparison of the pharmacokinetic parameters (AUC0-infinity, AUCss,0-tau, tmax, Cmax, Css,min, Css,av, MRT, etc.) calculated from the time-plasma concentration curve, moreover on the basis of clinical results, there was no significant difference between the two preparations. In conclusion, the relative bioavailability of Cordaflex and Adalat 20 mg retard tablets did not show significant difference after single and repeated administration.