Two intraindividual comparative single-dose studies were carried out under carefully controlled conditions on 8 (10) healthy volunteers in order to establish the bioequivalence of 4-amino-5-chloro -N- (2-diethyl-aminoethyl) -2- methoxy-benzamide (metoclopramide) the active principle of Gastrosil tablets and drops, in comparison to the respective formulations, i.e. tablets and drops of a reference drug. In an additional, open single-dose study the pharmacokinetics of metoclopramide were investigated after administration of a newly developed sustained-release dosage form. The analysis of unchanged metoclopramide in plasma was carried out using high-performance liquid chromatography. A 2-compartment open model was taken as a basis for the calculation of the plasma concentration curves and the pharmacokinetic parameters. All oral dosage forms investigated are bioequivalent. Comparing the present results to literature data following i.v. administration of the drug, bioavailabilities between 54-75% could be calculated. The initial distribution of the drug following administration of tablets and drops is very rapid, the terminal elimination half-lives ranges from 4.1-5.7 h and the apparent volumes of distribution were found to be 5.2-5.8 l/kg body weight.