We have previously reported that Korean schizophrenic patients hove low production of IL-2 in vitro suggestive of autoimmunity to the pathogenesis of the disorder. In an attempt to further explore this issue, we measured in vivo serum levels of interleukins(IL-$1{eta}$, IL-2, and IL-6) using a quantitative "sandwich" enzyme immunoassay(ELISA) in 26 male schizophrenic patients and in 26 age-matched normal controls. Patients met DSM-IV criteria for schizophrenia and were drug free for at least six months. The severity of symptoms was assessed by SANS and SAPS. We found a significant increase of IL-2 level(p<0.05) in schizophrenic patients as compared with normal controls. There were significant positive correlations between IL-2, IL-6 levels and negative symptom scores. There were no correlations between age, age at onset, duration of illness and interleukin levels. Our results may support the hypothesis of viral-autoimmune dysfunction in schizophrenia. IL-2 or IL-6 may be associated with specific clinical feature in schizophrenic syndrome, especially negative symptom.