In Europe, the compound 3,4-methylenedioxymethamphetamine (MDMA, Ecstasy, Adam), in addition to cannabis, is the most abused illicit drug at all-night "techno" parties. Methods for the determination of MDMA and its metabolites, 4-hydroxy-3-methoxymethamphetamine (HMMA), 3,4-dihydroxy-methamphetamine (HHMA), 3,4-methylenedioxyamphetamine (MDA), 4-hydroxy-3-methoxyamphetamine (HMA), and 3,4-dihydroxyamphetamine (HHA), in biological fluids were established. Plasma and urine samples were collected from two patients in a controlled clinical study over periods of 9 and 22 h, respectively. MDMA and MDA were determined in plasma and urine by reversed-phase high-performance liquid chromatography with diode array detection (HPLC-DAD) after solid-phase extraction on cation-exchange columns. Acidic or enzymatic hydrolysis was necessary to detect HMMA, HMA, HHMA, and HHA, which are mainly excreted as glucuronides. Gas chromatography-mass spectrometry (GC-MS) was used for confirmation. Sample extraction and on-disc derivatization with heptafluorobutyric anhydride (HFBA) were performed on Toxi-Lab SPEC solid-phase extraction concentrators. After administration of a single oral dose of 1.5 mg/kg body weight MDMA, peak plasma levels of 331 ng/ml MDMA and 15 ng/mL MDA were measured after 2 h and 6.3 h, respectively. Peak concentrations of 28.1 micrograms/mL MDMA in urine appeared after 21.5 h. Up to 2.3 micrograms/mL MDA, 35.1 micrograms/mL HMMA, and 2.1 micrograms/mL HMA were measured within 16-21.5 h. Conjugated HMMA and HHMA are the main urinary metabolites of MDMA.