Objective: To determine and estimate the efficacy of discharge planning interventions in mental health care from in-patient to out-patient treatment on improving patient outcome, ensuring community tenure, and saving costs. Method: A systematic review and meta-analysis identified studies through an electronic search on the basis of defined inclusion and exclusion criteria and extracted data. Results: Of eleven studies included, six were randomised controlled trials, three were controlled clinical trials, and two were cohort studies. The discharge planning strategies used varied widely, most were limited to preparation of discharge during in-patient treatment. Pooled risk ratios were 0.66 (95% CI = 0.51 to 0.84; P < 0.001) for hospital readmission rate, and 1.25 (1.07 to 1.47; P < 0.001) for adherence to out-patient treatment. Effect sizes (Hedge's g) were -0.25 (-0.45 to -0.05; P = 0.02) for mental health outcome, and 0.11(-0.05 to 0.28; NS) for quality of life. Conclusion: Discharge planning interventions are effective in reducing rehospitalisation and in improving adherence to aftercare among people with mental disorders.