Several precursors of testosterone and nandrolone introduced on the nutritional supplement market as performance enhancing drugs are banned in sports. Until now they are legally sold without a prescription in the US. Results of excretion studies with related compounds including 7-keto-DHEA and 1-androstenediol are presented. The main metabolites of 7-keto-DHEA are 7-hydroxylated compounds. The commercial 1-androstenediol preparation was contaminated with several other anabolic steroids. Oxidation of 1-androstenediol to 1-androstenedione seems to be the major renal metabolic pathway. Additionally contaminated nutritional supplements containing banned substances not indicated on the label were administered. The results of the excretion studies indicate that after the intake of amounts substantially lower than the recommended dose athletes can fail a doping test for periods up to 120 h.