The 17-epimers of the anabolic steroids bolasterone (I), 4-chlorodehydromethyltestosterone (II), fluoxymesterone (III), furazabol (IV), metandienone (V), mestanolone (VI), methyltestosterone (VII), methandriol (VIII), oxandrolone (IX), oxymesterone (X), oxymetholone (XI), stanozolol (XII), and the human metabolites 7 alpha,17 alpha-dimethyl-5 beta-androstane-3 alpha,17 beta-diol (XIII) (metabolite of I), 6 beta-hydroxymetandienone (XIV) (metabolite of V), 17 alpha-methyl-5 beta-androst-1-ene-3 alpha,17 beta-diol (XV) (metabolite of V), 3'-hydroxystanozolol (XVI) (metabolite of XII), as well as the reference substances 17 beta-hydroxy-17 alpha-methyl-5 beta-androstan-3-one (XVII), 17 beta-hydroxy-17 alpha-methyl-5 beta-androst-1-en-3-one (XVIII) (also a metabolite of V), the four isomers 17 alpha-methyl-5 alpha-androstane-3 alpha,17 beta-diol (XIX) (also a metabolite of VI, VII, and XI), 17 alpha-methyl-5 alpha-androstane-3 beta,17 beta-diol (XX), 17 alpha-methyl-5 beta-androstane-3 alpha,17 beta-diol (XXI) (also a metabolite of V, VII, and VIII), 17 alpha-methyl-5 beta-androstane-3 beta,17 beta-diol (XXII), and 17 beta-hydroxy-7 alpha,17 alpha-dimethyl-5 beta-androstan-3-one (XXIII) were synthesized via a 17 beta-sulfate that spontaneously hydrolyzed in water to several dehydration products, and to the 17 alpha-hydroxy-17 beta-methyl epimer. The 17 beta-sulfate was prepared by reaction of the 17 beta-hydroxy-17 alpha-methyl steroid with sulfur trioxide pyridine complex. The 17 beta-methyl epimers are eluted in gas chromatography as trimethylsilyl derivatives from a capillary SE-54 or OV-1 column 70-170 methylen units before the corresponding 17 alpha-methyl epimer. The electron impact mass spectra of the underivatized and trimethylsilylated epimers are in most cases identical and only for I, II, and V was a differentiation between the 17-epimers possible. 1H nuclear magnetic resonance (NMR) spectra show for the 17 beta-methyl epimer a chemical shift for the C-18 protons (singlet) of about 0.175 ppm (in deuterochloroform) to a lower field. 13C NMR spectra display differences for the 17-epimeric steroids in shielding effects for carbons 12-18 and 20. Excretion studies with I-XII with identification and quantification of 17-epimeric metabolites indicate that the extent of 17-epimerization depends on the A-ring structure and shows a great variation for the different 17 alpha-methyl anabolic steroids.