The role of Complement factors in the pathogenesis of psychiatric disorders is enormous, but the data on levels and functions of complement factors in patients with schizophrenia are scanty and conflicting. To address this issue, levels of Complement regulators (C1 inhibitor and C3 activator) and complement factors (C1q, C3c, C4 and C5) were determined in the serum of newly diagnosed drug free schizophrenic patients, schizophrenic patients on medication and healthy subjects using immune-plates. C1q was significantly reduced in newly diagnosed schizophrenic patients or schizophrenic patients on medication compared with the controls. C3c was significantly reduced in newly diagnosed schizophrenic patients compared with controls or schizophrenic patients on medication. The levels of C3 activators, C1 inhibitors and C4 were similar in the two groups of schizophrenic patients compared with the controls. It may be concluded from this study that C1q is deficient in schizophrenic patients; and that C3c may differentiate newly diagnosed schizophrenia from schizophrenic patients on medication.