Objective The 19-Norandrosterone (19NA) and 19-Noretiocholanolone (19NE) are endogenous steroids abused as dope.The aim of this study was to investigate the detection of 19NA and 19NE using isotope ratio mass spectrometry.Methods Two male volunteers were recruited.Each volunteer was orally administered a single dose of 20 mg of nandrolone,and their urine samples were collected after administration.The analyses of urinary concentrations and isotope ratios of 19NA and 19NE were performed.Results Concentrations of 19NA and 19NE increased rapidly after administration,and their isotope ratios decreased to the value of the drug ingested.Conclusion The intake of nandrolone has no effect on the isotope ratios of pregnanediol,androsterone and etiocholanolone.The urine samples were positive within 27 hours after administration.