A series of acylated derivatives of 3,4-methylenedioxy-methamphetamine (3,4-MDMA) are prepared and evaluated in gas chromatography-mass spectrometry (GC-MS) studies. The perfluoroalkyl amides of 3,4-MDMA show the lowest GC retention, while the aromatic amides such as the benzamide show the greatest retention on the dimethylpolysiloxane stationary phase (Rtx-1). The mass spectral properties of the acetyl, propionyl, and butyryl derivatives all show a base peak at m/z 58 which is the base peak for the underivatized 3,4-MDMA. All acylated derivatives provide mass spectral information (m/z 162) to identify the three-carbon side chain for 3,4-MDMA. The perfluoroalkyl amides yield several unique mass spectral fragments for specific identification of 3,4-MDMA. MS fragmentation pathways are illustrated and validated using analogous deuterated derivatives. A combination of excellent chromatographic properties and unique mass spectral fragments allows the perfluoroalkyl amides to provide maximum specific structural information in the GC-MS analysis of 3,4-MDMA.