A series of 1-methyl-3,5-diphenyl-4,5-dihydro-1H-pyrazoles (3a–k and 4a–u) were designed, synthesized, and evaluated for their inhibitory efficacy towards the two hMAO isoforms. Most of the derivatives were found to be potent and selective hMAO-B inhibitors. In particular, derivative 3g showed greater hMAO-B affinity than selective inhibitor selegiline coupled with high selectivity index (SI = 145)