3,4-Methylenedioxymethamphetamine (MDMA), or ecstasy, is excreted as unchanged drug, 3,4-methylenedioxyamphetamine (MDA), and free and glucuronidated/sulfated 4-hydroxy-3-methoxymethamphetamine (HMMA), and 4-hydroxy-3-methoxyamphetamine (HMA) metabolites. The aim of this paper is to describe the pattern and timeframe of excretion of MDMA and its metabolites in urine. Placebo, 1.0 mg/kg, and 1.6 mg/kg oral MDMA doses were administered double-blind to healthy adult MDMA users on a monitored research unit. All urine was collected, aliquots were hydrolyzed, and analytes quantified by gas chromatography-mass spectrometry. Median C(max), T(max), ratios, first and last detection times, and detection rates were determined. Sixteen participants provided 916 urine specimens. After 1.6 mg/kg, median C(max) were 21,470 (MDMA), 2229 (MDA), 20,793 (HMMA), and 876 ng/mL (HMA) at median T(max) of 13.9, 23.0, 9.2 and 23.3 h. In the first 24 h, 30.2-34.3% total urinary excretion occurred. HMMA last detection exceeded MDMA's by more than 33 h after both doses. Identification of HMMA as well as MDMA increased the ability to identify positive specimens but required hydrolysis. These MDMA, MDA, HMMA, and HMA pharmacokinetic data may be useful for interpreting workplace, drug treatment, criminal justice, and military urine drug tests. Measurement of urinary HMMA provides the longest detection of MDMA exposure yet is not included in routine monitoring procedures.