Abstract： Objective To investigate the inhibitory effect of dacarbazine and an oncolytic adenovirus carrying interleukin-24 (IL-24) on transplanted melanoma in nude mice.Methods Nude mice were inoculated with human A375 melanoma cells to establish a model of malignant melanoma.Then,the mice were divided into 4 groups to be treated with an oncolytic adenovirus carrying interleukin-24 (ZD55-IL-24),dacarbazine,the combination of ZD55-IL-24 and dacarbazine,and phosphate buffer (PBS),respectively,for 3 days.Seven days after the end of the treatment,some mice were sacrificed followed by the determination of IL-24 and E1A protein levels in tumor tissue by Western blot.The tumor volume was measured on a daily basis for 30 days.Results IL-24 and E1A were highly expressed in melanoma cell-bearing nude mice treated with ZD55-IL-24 and dacarbazine.At 30 days after the inoculation,the average volume of transplanted melanoma was (2346.5 ± 576.0) mm3 in the combination group,significantly different from that in the ZD55-IL-24 group ((4141.6 ± 1348.2) mm3,P ＜ 0.05),dacarbazine group ((5230.1 ± 922.8) mm3,P ＜ 0.05),and the control group ((7135.1 ± 1002.3) mm3,P ＜ 0.05).Conclusion The ZD55-IL-24 in combination with dacarbazine exhibits a remarkably inhibitory effect on the proliferation of melanoma transplanted into nude mice.