The ciliary neurotrophic factor (CNTF) gene is considered a candidate gene for schizophrenia, in view of the neurodevelopmental hypothesis of the disorder. Recently, controversial results regarding an association between psychiatric disorders; mainly schizophrenia, and a null mutation of the CNTF gene were reported. We investigated this mutation in 138 Japanese patients with schizophrenia and 140 healthy control subjects. No significant difference was observed in allele frequencies or genotype distribution between the patients and control subjects. Our results did not provide evidence for the involvement of the null mutation of the CNTF gene in the development of schizophrenia.