This study presents and discusses the nuclear magnetic resonance (NMR) spectroscopic and mass spectroscopic data of the designer drug 3,4-methylenedioxypyrovalerone (MDPV), a drug variant of pyrovalerone. MDPV was first seized in Germany in the year 2007. The structure elucidation of the aliphatic part of MDPV was carried out by product ion spectroscopy of the immonium ion with m/z 126 formed after electron ionization, and by 1D (1)H and (13)C NMR spectroscopy. Additional two-dimensional NMR spectroscopy was used to verify the structure of the alkyl side chain, and to determine the methylenedioxy position in the aromatic ring.