An open, randomized cross-over trial was performed in 20 healthy volunteers to evaluate the relative bioavailability and the pharmacokinetics of myrtol standardized, the active ingredient of Gelomyrtol and Gelomyrtole forte capsules (abbreviated as GE and GF, respectively, in the following text). The male subjects, aged 19 to 42 years, were given in a randomized manner 1 capsule of GE (120 mg myrtol stand.) uncrushed, 1 capsule of GE crushed, 1 capsule of GF (300 mg myrtol stand.) uncrushed and 1 capsule of GF crushed on 4 different days. The time of administration was always about 8 a.m. and the medication had to be swallowed with 200 ml water. The 4 study sessions were separated (correction of spearated] by at [correction of a] least 6 days. Prior to and 15, 30, 45, 60, 75, 120, 150 min and 3, 4, 5, 8, 12 and 24 h after medication at least 10 ml blood were taken from an antecubital vein. The blood samples were centrifuged within 20 min, the plasma was separated, and transferred into tubes and immediately deep-frozen at -20 degrees centigrade. From GE capsules cineol as main component was absorbed to 93,2% and from GF capsules to 95,6% based on the comparison of the uncrushed with the crushed capsules. The geometric mean of Cmax was 72,4 ng/ml for GE uncrushed capsules, a value of 33% below that for the crushed ones. The time to peak (tmax) was three times higher. With GF Cmax reached 238,2 ng/ml for the uncrushed capsules, a value of 36% below the one for the crushed ones and tmax was 67% higher. The time until the appearance of measurable plasma concentrations (tlag) was 7 and 5 times higher, respectively. These results show, that the main components of myrtol standardized, the active ingredient of GE and GF, are absorbed about 100% compared to the liquid form of administration (crushed capsule). The enteric coating of the capsules produces lower plasma peak-concentrations at later time points. This results in a plateau-like phase of the concentration/time curve between the 2nd and the 8th hour after application and reveals a considerable therapeutic advantage of the enteric coating.