P-glycoprotein (P-gp), encoded by the ABCB1 gene, confers multi-drug resistance to a variety of antineoplastic agents, for example, paclitaxel. Recently, the G1199T/A polymorphism in the ABCB1 gene was shown to be important for the function of P-gp as well as for the resistance to several chemotherapeutic agents in vitro. We analyzed the allelic distribution of the G1199T/A and other polymorphisms in exons 11 and 12 of the ABCB1 gene in ovarian cancer patients treated with paclitaxel and carboplatin in order to evaluate their predictive value in vivo. The SNPs C1236T, G1199T/A, and A1308G were determined using Pyrosequencing in 51 patients with advanced ovarian cancer and correlated to the progression free survival. The G1199T/A SNP was found to affect the progression free survival. Although only two heterozygous (G/A) patients were found their mean progression free survival was only 2 months as compared to 19 months for the wild-type patients. This is in accordance with the higher resistance for the 1199A genetic variant found in vitro. Genotyping of the ABCB1 gene may be important for determining the tumor resistance to paclitaxel and provide useful information for individualized therapy.