Objective: To study the effect on cytotoxicity and drug resistance by blocking ERCCl gene expression in o-varian cancer cell lines. Methods: ERGC1 antisense expression vector was constructed and transfected into human ovarian cancer cell lines. Northern blotting and Western blotting were used to detect the RNA and protein expression level in the cells. Luciferase assay system was used to reveal the host cell reactivation function. MTT assay was used to study the effect on cytotoxicity and drug resistance in the cell lines. Results: After transfection of the antisense ERCCl, Northern and Western blotting indicated that the RNA and protein expression level of ERCCl was obviously decreased. Luciferease assay showed reduced DNA-damage repair capacity as assessed by host cell reactivation. MTT assay also showed decreased drug resistance to cisplatin in the lines. Conclusion: Transfection of antisense ERCCl may enhance the cisplatin cytotoxicity by disturbing the NER pathway in cisplatin-resistant cell lines.