The association between the epsilon 4 allele of the apolipoprotein E (APOE) gene and Alzheimer's disease (AD) has been reported. In order to examine if the epsilon 4 allele may play a role also in schizophrenia, another mental disorder, patients (n = 87) and control subjects (n = 57) were genotyped for APOE. No significant difference was found between the groups. The data indicate that the APOE gene is not of major importance for the genesis of schizophrenia.