The present study was done in thirty-six hospitalized psychiatric patients (20 schizopherenia and 16 major psychotic unipolar depressive episode cases) meeting DSM-III-R criteria in Psychiatry Clinics, Atatürk University, School of Medicine, Research Hospital in 1992. In each patient group serum Ig G, A, M levels were measured before and after treatment. Student's t test was used for statistical analysis. The reduction in Ig levels are statistically significant in posttreatment period when compared to pretreatment period in each group (in schizophrenics t=2.58, p<0.05 ; t=2.41, p<0.05; t=2.96, p<0.05, in depressive patients t=3 .1, p<0.01 ; t=3.54, p<0.01 ; t=2.1, p<0.05 respectively). On the other hand, no difference is found in prettreatment Ig levels of schizophrenic and major depressive episodic patients (t=0.3, p>0.05; t=0.4, p>0.05 ; t=0.6, p>0.05 respecetively). It is concluded that increased serum. Ig levels in schizophrenia and major depression, as major psychiatric disorders, may be decreased by remission, and these disorders may have a similar immunological pattern.