AbstractRecognizing the robust sex differences in schizophrenia prevalence, the selective estrogen receptor modulator (SERM) raloxifene is a likely candidate for augmentation therapy in this disorder. Therefore, a systematic search was performed using PubMed (Medline), Embase, PsychInfo, and Cochrane Database of Systematic Reviews. Randomized controlled trials investigating the effect of raloxifene in schizophrenia spectrum disorders were included in the quantitative analyses. Outcome measures were psychotic symptom severity, depression, and cognition. Meta-analyses were performed using Comprehensive Meta-Analysis software. A random-effects model was used to compute overall weighted effect sizes in Hedges’ g. Nine studies were included, investigating 561 patients with a schizophrenia spectrum disorder. Raloxifene was superior to placebo in improving total symptom severity (N = 482; Hedge’s g = .57, p = 0.009), as well as positive (N = 561; Hedge’s g = 0.32, p = 0.02), negative (N = 561; Hedge’s g = 0.40, p = 0.02), and general (N = 526; Hedge’s g = 0.46, p = 0.01) subscales, as measured by the Positive and Negative Syndrome Scale. No significant effects were found for comorbid depression and cognitive functioning. Altogether, these results confirm the potential of raloxifene augmentation in the treatment of schizophrenia.