Objective: Ceruloplasmin is a protein in the human serum that is synthesized by hepatocytes, but extrahepatic gene expression in the brain, lung, spleen, and testis has also been reported. Ceruloplasmin contains approximately 95% of serum copper and it carries copper from liver to numerous tissues. Ceruloplasmin level reflects largely the copper concentration of the serum. However, ceruloplasmin has also an antioxidant function that is known as the acute phase reactant. Additionally, ceruloplasmin has a role in the oxidation of serotonin, epinephrine, and norepinephrine. Abnormalities in ceruloplasmin levels have been associated with several neurodegenerative diseases. Moreover, the alteration of plasma ceruloplasmin levels has been linked to schizophrenia and its some clinical characteristics including acute or chronic phase, the length of the disease or whether the patients on treatment or not. However, there exists a controversy on relationship between the plasma level of ceruloplasmin and schizophrenia. There are number of reports on the increased or decreased and/or normal level of plasma ceruloplasmin in association with schizophrenia, These differences may have been originated from the usage of different measurement methods, clinical situations, and ethnobiological differences. In the present study, we aimed to investigate the association between plasma ceruloplasmin level and schizophrenic in Turkish patients.