OBJECTIVE: 5-HTTLPR (5-HT transporter-linked polymorphic region), located in the promoter region of 5-HT transporter gene, was reported to be associated with several neuropsychiatric illnesses. In this study, we investigated the genotype distribution and allele frequency of serotonin transporter gene 5-HTTLPR in schizophrenic patients and normal controls using an independent Korean sample. METHODS: Subjects were 156 schizophrenic patients fulfilling the DSM-IV criteria for schizophrenia who had taken antipsychotics for at least 6 months and 96 normal controls who had no past and family history of psychiatric illnesses. Two negative symptoms of PANSS, blunted affect and emotional withdrawal, were rated in all patients by two experienced psychiatrists. We examined the genotype distribution and allele frequency of the serotonin transporter gene 5-HTTLPR in all subjects, using polymerase chain reaction (PCR) of genomic DNA with primers flanking the promoter regions of the 5-HTT gene. Between-group comparisons of the genotype distribution and allele frequency were performed by using score test for trend, Fisher's exact test, and chi-square test. RESULTS: There was no significant difference in 5-HTTLPR genotype distribution and allele frequency between schizophrenic patients and normal controls. There was also no significant difference in 5-HTTLPR genotype distribution and allele frequency between schizophrenic patients with and without the two negative symptoms, blunted affect or emotional withdrawal, respectively. CONCLUSION: These results suggest that 5-HTTLPR polymorphism had no significant association with schizophrenia and negative symptoms in a Korean sample.