Abstract: To investigate the relationship between genetic polymorphism in 105 codons of the glutathione S-transferase P1 ( GSTP1 ) gene and patient sensitivity to platinum-based chemotherapy. Method: A total of 50 cancer patients were enrolled in our study, which were confirmed by pathologic diagnosis and CT scanning to have measurable lesions and then subjected to platinum-based chemotherapy. Peripheral blood was obtained before the therapy, and direct sequencing was performed to detect single nucleotide polymorphisms ( SNPs ) in the 105 codons of GSTP1 in peripheral blood. The clinical responses of these patients after 2 to 4 cycles of chemotherapy were observed. The relationship between SNPs of the GSTP1 gene and clinical responses was analyzed. Results: No correlation was found between the distribution of GSTP1 genotypes and different cancers ( P > 0.05 ). The response rates to chemotherapy in patients with the Ile/Ile, Ile/Val, and Val/Val genotypes in the 105 GSTP1 codons were 20.0%, 36.4% and 87.5%, respectively. The response rate was higher in the patients with the homozygous Val/Val mutant genotype than in those with the Ile/Ile or Ile/Val genotypes ( P  < 0.05 ). Conclusion: Single nucleotide polymorphisms of the GSTP1 gene may be associated with sensitivity to platinum-based chemotherapy.