Peiminine is a compound that is isolated from Bolbostemma paniculatum (Maxim) Franquet (Cucurbitaceae family), which has demonstrated antitumor activities. Its precise molecular mechanisms underlying antitumor activity remain elusive. In this study, peiminine-induced apoptosis towards human hepatocellular carcinoma and its molecular mechanisms were investigated. MTT assay was employed to assess anticancer effects of peiminine at concentrations of 2, 4, 6, 8, 10, 12, and 14 μg/ml after 24, 48, or 72 h. Nuclear staining and flow cytometry were carried out to further assess apoptosis. Mitochondrial membrane potential evaluation and Western blot analysis were performed to investigate the mechanism of peiminine-induced apoptosis. Peiminine reduced the viability of HepG2 cells in a time- and dose-dependent manner and had an IC ₅₀ of 4.58 μg/mL at 24h. Flow cytometry assessment indicated that peiminine markedly increased the cell number of apoptotic cells and the mitochondrial membrane potential dose-dependently in HepG2 cells. The results of Western blotting showed the expression of Bcl-2, procaspase-3, procaspase-8, procaspase-9, and PARP ₁ decreased in HepG2 cells treated with peiminine, while the expression of Bax, caspase-3, caspase-8, caspase-9, and cleaved PARP ₁ increased. The result suggest taht peiminine can induce apoptosis in human hepatocellular carcinoma HepG2 cells through both extrinsic and intrinsic apoptotic pathways.