Purpose of investigation: To survey genetic polymorphisms in the promoter region of the cytochrome P450 2C8 family gene (CYP2C8) in patients with epithelial ovarian cancer, and to determine whether the frequency of genetic polymorphisms and haplotypes in CYP2C8 are associated with efficacy and toxicity of anticancer drugs. Materials and Methods: The authors enrolled 43 patients diagnosed with epithelial ovarian cancer. They performed direct sequencing PCR using specific primers to detect single nucleotide polymorphisms (SNPs). They analyzed the efficacy and toxicity of chemotherapy in relation to SNP allele and haplotype patterns in patients. Results: The mutant alleles CYP2C8^*1D (-411T>C), CYP2C8^*1C (-370T>G), and CYP2C8^*1B (-271C>A) were found in the patient group, with an allele frequency of 0.37, 0.32, and 0.09, respectively. Of the 35 patients with advanced epithelial ovarian cancer, the CYP2C8^*1D mutation group had a significantly shorter disease-free interval after treatment (p = 0.020). Conclusions: CYP2C8^*1D mutation group had poorer prognosis and earlier onset of neurotoxicity.