Objective:To evaluate the inhibitory effect of Herceptin on HeLa,SiHa cells and to investigate the synergistic mechanism of Herceptin and Carboplatin.Methods:HeLa and SiHa cells were treated with Herceptin(at 5,10,20,40,and 80 ?g/ml),Carboplatin(at 0.5,1,2,4,and 8 ?g/ml),and Her+CBP[(10+1),(20+2),and(40+4)?g/ml] separately.The untreated cells were taken as control.SP immunohistochemical method was used to detect the protein expression of HER-2/neu and downstream Ras oncogene.MTT method was used to study the inhibition effect of Herceptin on HeLa,SiHa cells and its synergetic effect with carboplatin.FCM was used to detect the cell apoptosis and cell cycle.The mRNA expression of her-2/neu and ras were assessed by RT-PCR;the protein expression of HER-2/neu and Ras were studied by Western blotting.Results:Herceptin significantly inhibited cervical cancer cells proliferation,and there was a synergistic effect when combined with carboplatin(P