Recently, on the basis of the effects of serotonin (5-HT) reuptake inhibitors in obsessive-compulsive disorder (OCD) treatment, several candidate genes related to 5-HT regulation have been hypothesized to play an important role in the development of OCD. One of them is 5-HT transporter gene. Therefore, the aims of this study were to investigate the associations between 5-HT transporter polymorphism and OCD. One hundred and twenty-four OCD patients and 171 normal controls participated in this study. Genomic DNA was extracted from their blood. Comparison of the genotypes and allele frequencies of the SERTPR polymorphism between the OCD group and the control group was made. Using principal component analysis, we derived four factors from thirteen main contents of the Y-BOCS checklist and investigated the association between these four factors and the SERTPR polymorphism. In this case-control study, we could not find any associations between the SERTPR polymorphism and the development of OCD. In the OCD group, patients with the L genotype had higher scores for the religious/somatic factor than with the S genotype. In conclusion, the SERTPR polymorphism does not affect the development of OCD. But SERTPR polymorphisms affect certain factors of OC symptoms. Moreover, the factor analytic approach used in the present study has identified meaningful symptom dimensions to help guide future research.