The recent possible neurodevelopmental etiology of schizophrenia makes the neurotrophin-3 (NT-3) gene an interesting candidate locus. We studied the allelic distributions of dinucleotide repeat polymorphism at the NT-3 gene locus in 70 patients with schizophrenia and in 70 controls. A highly significant difference between the two groups was observed at the allele A3. Even Bonferroni's correction was used, the difference was still significant. Individuals with homozygous or heterozygous for the allele A3 had a 2.4-fold increased risk of schizophrenia. Determination of NT-3 genotype may help to identify those at greater risk of schizophrenia. Furthermore, this finding supports evidence implicating neurodevelopmental deficit in the pathogenesis of this disorder.