The present study sought to assess biomarkers of inflammation in stable patients with schizophrenia (SZ) on clozapine therapy. We recruited 60 outpatients with SZ and 60 healthy controls, matched for sex and age. Compared with controls, patients had significantly increased concentrations of interleukin-6 and tumor necrosis factor-α. Interestingly, patients on simvastatin had lower interleukin-6 levels compared with patients not on simvastatin and controls. This study corroborated previous evidence for increased inflammatory biomarkers in SZ and detected a potential anti-inflammatory action of simvastatin in patients with a clinical diagnosis of SZ on clozapine therapy.