This article discusses the use of N-acetylcysteine (NAC) for treating schizophrenia (1). Oxidative stress and neuroinflammation have recently been focused on the pathological hypotheses of schizophrenia. NAC is a precursor of endogenous antioxidant glutathione and has antioxidant, anti-inflammatory, and neuroprotective properties. In randomized controlled trials, treatment with NAC as an add-on to antipsychotics showed beneficial effects and safety profiles in patients with chronic schizophrenia. The results of a recent preclinical study using a neurodevelopmental model of schizophrenia suggest that NAC may have promising effects in an early stage of schizophrenia and an at-risk mental state. The authors conclude that there is little clinical evidence for the efficacy and safety of NAC at these stages of schizophrenia and summarize the evidence available.