An increasing body of evidence suggests a role for the immune system in the pathogenesis of schizophrenia. The information concerning the effects of antipsychotics on cytokine profiles are limited and often controversial in particular regarding novel antipsychotics. The authors first investigated the production of various cytokines [interleukin (IL)-2, IL-4, IL-10, interferon (INF)-gamma] in drug-free (n = 12) and drug-naive (n = 3) schizophrenic patients and in healthy controls (n = 33) and then the modifications of cytokines values during a 3-month period of treatment with risperidone. In the baseline condition, the production of IL-2 and INF-gamma was significantly higher (P = .023 and .026, respectively) in patients than in controls. In the same patients, the use of risperidone was associated with augmented IL-10 (a suppressor of Type I cytokines) and decreased INF-gamma production. This modification suggests that clinical improvement is associated with a reduction in the inflammatory-like situation present in not currently treated schizophrenic patients.