Purpose: Farms are increasingly used in mental healthcare. This study aimed to systematically review the evidence on the effectiveness of farm-based interventions for patients with mental disorders. Methods: Controlled and uncontrolled studies of farm-based interventions were included. Within- and between group effect sizes were calculated. Qualitative data were summarized using thematic synthesis. The review followed the PRISMA, Cochrane and COREQ standards. Results: The eleven articles included reported results of five studies, three of which were randomized control trials (RCTs). Overall, 223 patients with depressive disorders, schizophrenia or heterogeneous mental disorders attended three types of farms-based interventions. Favourable effects on clinical status variables were found in one study in patients with depressive disorders that did not respond to medication and/or psychotherapy, and in one RCT in patients with schizophrenia. Assessment of rehabilitative effects (functioning and quality of life) was limited and yielded conflicting results. Patients' experiences revealed that social and occupational components of interventions were perceived as beneficial, and provided insights into how farm-based interventions may facilitate recovery. Conclusions: Our results suggest that the farm environment should be considered, especially for patients with mental disorders who do not achieve an adequate response with other treatment options. Further research is needed to clarify potential social and occupational benefits.Implications for RehabilitationDespite the developments in mental healthcare, in many countries farms still play a role in the provision of psychiatric rehabilitation services.Farm-based interventions can alleviate psychiatric symptoms in patients with persistent mental disorders and can facilitate mental health recovery.The social and occupational aspects of the farm-based interventions are central to the experiences of mental health recovery.