After oral administration of metandienone (17 alpha-methyl-androsta-1,4-dien-17 beta-ol-3-one) to male volunteers conjugated metabolites are isolated from urine via XAD-2-adsorption, enzymatic hydrolysis and preparative high-performance liquid chromatography (HPLC). Four conjugated metabolites are identified by gas chromatography-mass spectrometry (GC/MS) with electron impact (EI)-ionization after derivatization with N-methyl-N-trimethyl-silyl-trifluoroacetamide/trimethylsilyl-imidazole (MSTFA/TMS-Imi) and comparison with synthesized reference compounds: 17 alpha-methyl-5 beta-androst-1-en-17 beta-ol-3-one (II), 17 alpha-methyl-5 beta-androst-1-ene-3 alpha,17 beta-diol (III), 17 beta-methyl-5 beta-androst-1-ene-3 alpha,17 alpha-diol (IV) and 17 alpha-methyl-5 beta-androstane-3 alpha,17 beta-diol (V). After administration of 40 mg of metandienone four bis-hydroxy-metabolites--6 beta,12-dihydroxy-metandienone (IX), 6 beta,16 beta-dihydroxy-metandienone (X), 6 beta,16 alpha-dihydroxy-metandienone (XI) and 6 beta,16 beta-dihydroxy-17-epimetandienone (XII)--were detected in the unconjugated fraction. The metabolites III, IV and V are excreted in a comparable amount to the unconjugated excreted metabolites 17-epimetandienone (VI), 6 beta-hydroxy-metandienone (VII) and 6 beta-hydroxy-17-epimetandienone (VIII). Whereas the unconjugated excreted metabolites show maximum excretion rates between 4 and 12 h after administration the conjugated metabolites III, IV and V are excreted with maximum rates between 12 and 34 h.