Fourteen novel steroidal C-17 pyrazolinyl derivatives 9a-g and 10a-g were synthesized from commercially available progesterone and tested for their cytotoxic activity against brine shrimp (Artemia salina) and three human cancer cell lines (NCI-H460, HeLa, and HepG2). Some of these synthetic compounds exhibited significant cytotoxic activity, and treatment of HeLa cells with compound 10b resulted in the cell population arrest in the S phase. A structure-activity relationship was discussed.