Background: Prader-Willi Syndrome (PWS) is a rare genetic disorder. To improve the health deterioration of PWS, investigating optimal treatment options for PWS is required. Thus, we aimed to evaluate the efficacy of pharmacotherapies compared with supportive care or placebos in patients with PWS. Methods: PubMed and EMBASE databases were used to search for randomized controlled trials (RCTs) evaluating the efficacy of pharmacotherapy in PWS patients. Only RCTs that evaluating the efficacy of pharmacotherapy in PWS patients were retrieved. Results: A total of 26 studies were included to evaluate body composition, hormones, glucose levels and hyperphagia behavioral status. Pharmacological treatment group showed a significant decrease of body fat (mean difference (MD): -6.32, 95% confidence interval (CI): -10.58 to -2.06, p=0.004), a significant increase of lean body mass (LBM) (MD: 1.86, 95% CI: 1.43 to 2.30, p<0.00001) and insulin-like growth factor 1 (IGF-1) levels (MD: 241.62, 95% CI: 68.59 to 414.64, p=0.006) compared with the control group. Nevertheless, based on other outcomes evaluated by the current systematic review, pharmacological options showed different efficacy in treating PWS. Conclusion Pharmacological therapies were effective to decrease significantly in body fat and increase significantly on LBM and IGF-1 levels in patients with PWS. However, still, individualized therapies should be considered in real-world practice in PWS treatment.