Brain-derived neurotrophic factor (BDNF) has been suggested to be involved in the etiology of schizophrenia. There is a line of evidence that disruption of neurotrophins could play a role in the etiology of schizophrenia, and antipsychotics show their effect by altering levels of neurotrophins. The aim of this study was to evaluate the effect of antipsychotics on serum BDNF levels and their relationship with the symptoms in patients with schizophrenia. Twenty-two schizophrenia patients were enrolled in the study. The control group consisted of 22 age- and sex-matched physically and mentally healthy volunteers (7 male, 15 female). Serum BDNF levels and the positive and negative syndrome scale (PANSS) scores were recorded at baseline and after 6 weeks of treatment. Serum BDNF levels were also recorded in the control group. Schizophrenia patients who failed to meet 30% improvement in PANSS score were excluded from the study. The baseline serum BDNF levels of schizophrenia patients were lower than those of controls (t=4.56; df=21; p<0.001). There was no correlation between serum BDNF levels and PANSS scores inpatients with schizophrenia (p>0.05). Although PANSS (for positive symptoms p<0.001, for negative symptoms p<0.001) and general psychopathology (t=20.9; df=22;p<0.001) scores improved significantly after 6 weeks of antipsychotic treatment; there was no change in BDNF levels in patients' serum (p>0.05). Our results support the view that BDNF would be associated with schizophrenia. However, we could not conclude that treatment with antipsychotics alters serum BDNF levels in patients with schizophrenia. (C) 2004 Elsevier Inc. All rights reserved.