PARP-1-IN-3, a benzamide derivative, is a potent PARP-1 inhibitor with IC 50 values of 0.25 nM and 2.34 nM for PARP-1 and PARP-2, respectively. PARP-1-IN-3 induces apoptosis and arrest cell cycle at G2/M phase. PARP-1-IN-3 can be used in research of cancer.