In the crystal structure of (E)-8-(3-chlorostyryl)-1,3,7-trimethylxanthine (CSC) [systematic name: (E)-8-(3-chlorostyryl)-1,3,7-trimethyl-3,7-dihydro-1H-purine-2,6-dione], C16H15ClN4O2, the xanthine ring and the lateral styryl chain are coplanar. The crystal packing involves mainly parallel stacking of these planar molecules. The electrostatic potential calculated on the crystal structure conformation confirms the pharmacophore elements associated with MAO-B inhibition.