The elimination time of illicit drugs and their metabolites is of both clinical and forensic interest. In order to determine the elimination time for various drugs and their metabolites we recruited 52 volunteers in a protected, low-step detoxification program. Blood samples were taken from each volunteer for the first 7 days, daily, urine sample for the first 3 weeks, daily. Urine was analyzed using a fluorescence-polarization immunoassay (FPIA) and gas chromatography/mass spectrometry (GC/MS), serum using GC/MS. The elimination times of the drugs and/or their metabolites in urine and serum as well as the tolerance intervals/confidence intervals were determined. Due to the sometimes extremely high initial concentrations and low cut-off values, a few of the volunteers had markedly longer elimination times than those described in the literature. The cut-off values were as follows: barbiturates II (200 ng/ml), cannabinoids (20 ng/ml), cocaine metabolites (300 ng/ml), opiates (200 ng/ml). GC/MS detected the following maximum elimination times: total morphine in urine up to 270.3 h, total morphine and free morphine in serum up to 121.3 h, monoacetylmorphine in urine up to 34.5 h, 11-nor-9-carboxy-delta-9-tetrahydrocannabinol (THC-COOH) in urine up to 433.5 h, THC-COOH in serum up to 74.3 h, total codeine in urine up to 123 h, free codeine in urine up to 97.5 h, total codeine in serum up to 29 h, free codeine in serum up to 6.3 h, total dihydrocodeine (DHC) in urine up to 314.8 h, free DHC in urine up to 273.3 h, total and free DHC in serum up to 50.1 h. Cocaine and its metabolites were largely undetectable in the present study.