Minocycline is a caspase inhibitor, decreases inducible nitric oxide synthase, and has been shown to delay disease in a mouse model of neuropsychiatric disorders. Recently, we reported the antipsychotic effects of minocycline in patients with schizophrenia. In a pilot investigation, we administered minocycline (150 mg/d) for 4 weeks as an open-label adjunct to antipsychotic medication to 22 patients with schizophrenia. The Positive and Negative Syndrome Scale for schizophrenia showed statistically significant and robust clinical improvements with minocycline treatment, which were maintained at follow-up evaluation 4 weeks after the end of minocycline treatment. There were no adverse events. These results suggest that minocycline may be a safe and effective adjunct to antipsychotic medications, and that augmentation with minocycline may prove to be a viable strategy for "boosting" antipsychotic efficacy and for treating schizophrenia.