One hundred and eighty-one 3,4-methylenedioxymethamphetamine (MDMA) containing tablets were sampled from confiscated drugs received by the Taiwan National Bureau of Controlled Drugs for testing from 2002 to February 2005. Sample tablets demonstrated various colors and logos. The appearances, contents of MDMA and other components in these tablets were analyzed in order to understand the characteristics and trends of MDMA use. Samples were analyzed using GC-MS methodology. Deuterated internal standards were used for drug quantification. The MDMA contents varied from 16 to 193 mg/tablet. 66-71% of the tablets seized each year contained only MDMA, and the content of MDMA in MDMA only tablets varied from 89 to 133 mg/tablet. There was a decreasing trend in MDMA content in these tablets over time. Other components commonly found besides MDMA included caffeine (18%), methamphetamine (7%), 3,4-methylenedioxyethylamphetamine (MDEA) (7%) and amphetamine (4%). 3,4-Methylenedioxyamphetamine (MDA), ketamine, ephedrine, diazepam, chlorzoxazone and nicotinamide were also detected. During the study period, the number of other drugs found as well as the combinations of different drugs detected in these tablets increased.