Penta-acetyl geniposide, (Ac)(5)-GP, was produced by acetylation of a glycoside, isolated from an extract of Gardenia fructus. Previously, we have reported that C6 glioma cells could be inhibited in culturing as well as in bearing rats by treating with (Ac)(5)-GP. In this study, the effect and action of (Ac)(5)-GP on inducing cell death was examined in rat C6 glioma cells. Treatment of C6 glioma cells with (Ac)(5)-GP caused cell death, chromatin condensation, and internucleosomal DNA ladder. Also, cell cycle arrest at G(0)/G(1) phase revealed that (Ac)(5)-GP-induced cell death appears to be mediated by apoptosis. In addition, the results also showed that p53 and c-Myc increased due to treatment of (Ac)(5)-GP in a dose-response and time-dependent manner. Concomitant with the expression of p53 and c-Myc, decreased level of Bcl-2 and increased level of Bax protein were observed. These results suggest that cell death caused by (Ac)(5)-GP through apoptosis and cell cycle arrest at G(0)/G(1) may be associated with the induction of p53, c-Myc and may be mediated with apoptosis-related Bcl-2 family proteins.