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Objective: To discuss the effects of fatty acid amide hydrolase inhibitor URB597 on the apoptosis of human hepatoma cell line MHCC97H in vitro and its underlying mechanism. Methods: Different concentrations of URB597 （1, 5 and 10 μmol/L respectively） were administered to incubate MHCC97H. Flow cytometry was used to analyze the effects of URB597 on apoptosis in MHCC97H cells. Western-blot assay was applied to detect the levels of the apoptosis-inducing factors （AIF）, Bcl-2 and Bax with or without URB597. Caspase 3 detection kit was used to determine the activity of caspase 3. Results: （1） Following treatment with URB597 at different concentrations （1, 5 and 10 μmol/L） for 1, 4 and 7 days, the number of apoptotic cells was significantly increased with a time-dependent tendency. （2） After treatment with URB597 at different concentrations for 4 days, the activity of caspase 3 and AIF levels in the nucleus were increased significantly. （3） Following treatment with URB597 at a concentration of 10 μmol/L for 4 days, the expression level of Bcl-2 was obviously down-regulated, while Bax level was obviously up-regulated, when compared with those of the control group, and the Bcl-2/Bax ratio was obviously reduced. PI3K inhibitor LY294002 could also significantly reduce the Bcl-2/Bax ratio. However, as compared with the 10 μmol/L control level, its effect on the Bcl-2/Bax ratio was relatively lower. Conclusion: URB597 could enhance the apoptosis of MHCC97H cells by down-regulating the ratio of Bcl-2/Bax, further inducing caspase-dependent and caspase-independent cell apoptotic pathway, which was partial-dependent on PI3K/Akt signal pathway. [ABSTRACT FROM AUTHOR]