Forty-one stimulant drugs banned by the International Olympic Committee were studied after they were administered to human volunteers. The parent drugs and their metabolites in free or conjugated forms in human urine collected within 24 hours after administration of the drugs were extracted, separated and identified. The separation was performed on a capillary gas chromatograph with nitrogen-phosphorous detector, while the identification was achieved on a capillary gas chromatograph with mass-selective detector. The extract was injected into the gas chromatograph both directly and after derivatization with trifluoroacetic anhydride (TFAA) or N-methyl-N-trimethylsilyl trifluoroacetamide (MSTFA) as well as TFAA and MSTFA combined. The conjugated metabolites were studied after acid hydrolysis of the extract and then selectively derivatized as above. The results are summarized in 4 tables in the text.