Oral absorption of nifedipine determined from plasma concentrations was studied in 20 healthy subjects aged 19 to 40 years following application of a single soft gelatin capsule as a generic preparation (P) and a reference preparation (R) containing 10 mg nifedipine. Nifedipine was measurable in plasma 15 min after application and maximal concentrations occurred after 0.44 and 0.64 h (mean), respectively. Maximal concentrations Cmax varied between 46.4 and 251.0 ng/ml (median 100.7, mean 112.6) after P and between 35.5 and 279.7 ng.h/ml (median 115.8, mean 125.2) after R. Mean areas under the curves (AUC0-infinity) were 173.6 (median 151.4 P) and 188.6 ng.h/ml (median 163.1, R). The minor differences in the AUC values and Cmax values were not statistically significant. The shorter tmax after the generic preparation (p less than 0.05) is clinically unimportant. Since the bioavailability of P is 97% the two preparations are bioequivalent.