Objective : To evaluate the clinical efficacy of adjuvant sertraline treatment in chronic schizophrenic patients, we carried out a double-blind, placebo controlled study. Method : Thirty six inpatients who fulfilled DSM-III-R criteria for chronic schizophrenia were randomly assigned to sertraline and placebo groups in a double-blinded fashion. A history of at least 2 years of illness and at least six months of hospitalization were prerequisities for inclusion in the study. Patients were received sertraline 50mg or placebo for 8 weeks in addition to their routine haloperidol regimen. Positive and Negative Syndrome Scale (PANSS), Clinical Global Impression(CGI), Simpson-Angus Scale(S-A) were evaluated at 5 points ; baseline, 2, 4, 6, and 8 weeks of treatment. Results : The groups were controlled for age, gender, and length of illness. There were no significant differences in three PANSS factros(positive, negative, general), CGI, and S-A scale scores at any between sertaline and placebo treatment. Conclusion : This placebo controlled study showed no significant effects of sertraline on negative and positive symptoms in chronic schizophrenic patients.