Celecoxib augmentation therapy has been reported to enhance the rate of clinical response for patients with schizophrenia. This may be due in part to an effect of celecoxib in the immune dysfunction associated with schizophrenia. Given concerns about the safety of COX-2 inhibitors, studies investigating cytokine levels in medicated patients with schizophrenia are of public health importance. Twenty-eight schizophrenia subjects stabilized on olanzapine or risperidone were randomized to receive 8 wk of celecoxib (400 mg/d) or placebo. Serum soluble IL-2 receptor (sIL-2r) and in-vitro PHA-stimulated whole-blood cytokine production levels were measured at baseline, 1 wk, and 8 wk. Celecoxib augmentation did not alter any of the cytokine parameters measured for the overall study group. However, 1 wk of celecoxib augmentation increased TNF-alpha and IL-2 production levels in olanzapine-treated subjects. These elevations did not persist by week 8. Overall, celecoxib does not significantly modify cytokine levels in medicated schizophrenia subjects.