Abstract: Objectives To study the effects of fentanyl on growth and apoptosis of human hepatoma cell line bel-7404.Methods bel-7404 cells were divided into four test groups ( F1，F2，F3 and F4) and a control group (C).Cells in the four test groups were incubated in RPMI-1640 medium that contained different concentration of fentanyl respectively，such as 5，50，500 and 5000 ng/ml. Cells in the control group were cultured in RPMI-1640 medium only. After 24-hour incubation，morphological changes of the cells were observed by inverted microscope，the level of cell proliferation were evaluated by the methods of MTT and colony formation，and thedistribution of cell cycle and the apoptosis rate were detected with flow cytometry (FCM). Results The results from MTT and colony formation on the test groups were significantly lower than that of the control group(P＜0.01). The percentage of apoptosis was significantly higher in the test groups than that of the control group(P＜0.05).When the concentration of fentanyl was ≥50ng/ml，the rate of apoptotic cells increased gradually with the increasing concentration of fentanyl，and the ratio of cells in G₀/G₁ phase enhanced gradually and in S phase decreased gradually，which was significantly different from that of the control group (P＜0.05). Conclusion The inhibitory effect of fentanyl on growth of bel-7404 cell is dose-dependent. Fentanyl is able to block cell cycle and to induce apoptosis.

Key words: Fentanyl, Hepatoma, bel-7404, Apoptosis