Objective: The occurrence of some infections including Toxoplasma gondii during pregnancy or around the time of birth could be increased the risk of schizophrenia. The aim of the study was to evaluate the association between Toxoplasma infection and schizophrenia using serological and molecular methods. Method: From June 2016 to February 2017, 60 inpatients with schizophrenia (case group) among 456 inpatients and 40 healthy volunteers of the psychotic inpatients family (control group) were selected in Ibn-e-Sina and Hejazi hospitals, In Mashhad, Iran. The blood samples were taken for each person and examined by serological and molecular methods. Results: Overall seroprevalence T. gondii antibodies in case and control groups were 55% and 45%, respectively (P>0.05). The seroprevalence differences of the infection in case and control groups with regard to age and sex as risk factors were not significant (p>0.05). The results of study show that autumn born inpatients seroprevalence of infection was higher than same group in controls, and it was significant (P<0.05). The results of nested-PCR indicated that 21% of seropositive case group and 55.5% of seropositive control had Toxoplasma DNA in blood samples (P<0.05). Conclusions: It was concluded that T. gondii infection could not be considered as a risk factor to schizophrenia, despite the high frequency of Toxoplasma infection in the schizophrenic patients. It seems that the differential diagnosis of congenital and acquired toxoplasmosis in the schizophrenic patient is critical for the better understanding association between the T. gondii infection and schizophrenia

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