Abstract： Background Endostatin is a potent inhibitor of tumor angiogenesis.In the preliminary studies,we developed a mutant endostatin containing Arg-Gly-Asp-Arg-Gly-Asp (RGDRGD) sequences.In this study,we compared the antitumor effects of mutant endostatin and Bcl-2 antisense oligonucleotides both in combination and individually.Methods The artificially synthesized Bcl-2 ASODN (antisense oligonucleotides) included a translation-initiation site and was transfected into the bladder cancer cells by Lipofectamine.Cell growth was investigated by the tumor cell growth chart,MTT assay,caspase-3 activity detection assay,AO/EB fluorescein stain,and the annexin V-FITC apoptosis detection assay.In the in vivo study,UM-UC-3 bladder cancer cells were subcutaneously implanted into nude mice and the growth of tumor was examined.The ultrastructure of the tumor tissues in the treated and control groups were observed.Results The cell growth chart showed that the cell population of the treated combination group decreased by 52.04％compared to the control group.The inhibition rate of the treated combination group was (79.66±6.79)％,whereas those of the individual ASODN and ES groups were (53.39±3.22)％ and (50.22±5.46)％ respectively.In the caspase-3 activity detection using AO/EB fluorescein stain and annexin V-FITC apoptosis detection assay,the co-inhibitory effect was higher than the individual inhibitory effects (P＜0.05).There were significant differences in the inhibition of the solid tumor growth in the in vivo study.Conclusions Our findings indicated that Bcl-2 antisense oligonucleotides enhance the antitumor effects of mutant endostatin both in vitro and in vivo.We noted the synergistic effects of Bcl-2 antisense oligonucleotides combined with mutant endostatin.