A replication-defective recombinant adenovirus vector containing HSV-TK gene under the control of CEA promoter was constructed (AdCEATK). Titer of the purified recombinant adenovirus is about 10¹²pfu/ml. HeLa cell (CEA-negative cell) infected with AdCMVTK became sensitive to GCV, while HeLa cell infected with AdCEATK was not. On the contrary, the LoVo cell infected with both AdCMVTK and AdCEATK were sensitive to GCV. It was shown that CEA promoter has a good tumor-specificity. Significant bystander effect was observed in the AdCEATK/GCV system too. This system should be useful for tumor-specificity suicide gene therapy of CEA-positive tumors.