Recently, 3,4-methylenedioxyamphetamine derivatives have been encountered in the Italian illicit market, mainly in form of tablets. Among this class of substances small modifications of the molecule may result in a wide range of derivatives and analogs some of which are not yet listed as controlled substances in the Italian schedules. Due to the structural similarity some of these molecules have a gas chromatographic behavior and mass spectra that only slightly differ. In the present work, an analytical strategy is proposed to achieve the identification of analogs within this class of molecules. In seized material sent by the Court of Law of Rome to our laboratories a number of tablets engraved with different symbols (e.g., `Dollar', `Fido Dido' and `Bomb') were submitted to analysis in order to establish whether they contained drugs of abuse. The analytical techniques employed for this purpose were UV spectrophotometry and thin-layer chromatography which provided information suggesting that the tablets contained a methylenedioxyamphetamine. Gas chromatography with flame ionization detection indicated that the main ingredient differed from the molecules of the same class already known. Finally, capillary gas chromatographic–mass spectrometric analysis of the native molecules and their pentafluoropropionic acid derivatives, performed with both, electron impact and chemical ionization, allowed the identification, in each tablet, of three molecules: the N -methyl-1-(3,4-methylenedioxyphenyl)-2-butanamine (MDP-2-MB, MBDB), the 1-(3,4-methylenedioxyphenyl)-2-butanamine (MDP-2-B) and the N , N -dimethyl-1-(3,4-methylenedioxyphenyl)-2-butanamine (MDP-2-MMB).