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 7α,17α-dimethyl-5β-androstane-3α,17β-diol ( XIII) (metabolite of I), 6β-hydroxymetandienone ( XIV) (metabolite of V), 17α-methyl-5β-androst-1-ene-3α,17β-diol ( XV) (metabolite of V), 3'-hydroxystanozolol ( XVI) (metabolite of XII), as well as the reference substances 17β-hydroxy-17α-methyl-5β-androstan-3-one ( XVII), 17β-hydroxy-17α-methyl-5β-androst-1-en-3-one ( XVIII) (also a metabolite of V), the four isomers 17α-methyl-5α-androstane-3α,17β-diol ( XIX) (also a metabolite of VI, VII, and XI), 17α-methyl-5α-androstane-3β,17β-diol ( XX), 17a-methyl-5β-androstane-3α,17β-diol ( XXI) (also a metabolite of V, VII, and VIII), 17α-methyl-5β-androstane-3β,17β-diol ( XXII), and 17β-hydroxy-7α, 17α-dimethyl-5β-androstan-3-one ( XXIII) were synthesized via a 17β-sulfate that spontaneously hydrolyzed in water to several dehydration products, and to the 17α-hydroxy-17β-methyl epimer. The 17β-sulfate was prepared by reaction of the 17β-hydroxy-17a-methyl steroid with sulfur trioxide pyridine complex. The 17β-methyl epimer s are eluted in gas chromatography as trimethylsilyl derivatives from a capillary SE-54 or OV-1 column 70–170 methylen units before the corresponding 17α-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 17β-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 17α-methyl anabolic steroids.