STGC3, a novel tumor related gene, was cloned recently. The previous studies indicated that STGC3 can inhibit the proliferation of CNE2 cell line in vitro. To examine the effect of STGC3 on the tumorigenicity of CNE2 cell line and explore its mechanism in nude mice. The Tet/pTRE/CNE2-STGC3 cell line was planted under the front leg skin of nude mice and induced by doxycycline (Dox). The mRNA and protein level of STGC3 in transplanted tumor tissues were detected with RT-PCR and Western Blotting. The apoptosis ratio of the tumor cell was analyzed with flow cytometry. STGC3, Bcl-2 and Bax proteins were examined by immunohistochemistry method. The results indicated that high level of STGC3 expression can inhibit tumorigenicity of CNE2 cell line in nude mice. Tumor grew slowly, later and smaller. Cell apoptotic percentage increased. Bcl-2 protein expression was down-regulated and Bax protein expression was up-regulated in Tet/pTRE/CNE2-STGC3 cell line (P < 0.01). The data indicated that STGC3 had a role as a tumor suppressor gene in vivo, which was in line with the results in vitro.