Twenty-two pyrazoline derivatives were synthesized and tested for their human MAO (hMAO) inhibitory activity. Twelve molecules with unsubstituted ring A and substituted ring C (5–16) were found to be potent inhibitors of hMAO-A isoform with SIMAO-A in the order 103 and 104. Ten molecules with unsubstituted ring A and without ring C (21–30), in which eight molecules (21, 23–26, and 28–30) were selective