Prisoners have high rates of mental illness and the transition from prison to the community is a problematic time for the provision of mental health services and a range of negative outcomes have been identified in this period. A systematic review was conducted to identify interventions for prisoners with diagnosed mental health conditions that targeted this transition period. Fourteen papers from 13 research studies were included. The interventions identified in this review were targeted at different stages of release from prison and their content differed, ranging from Medicaid enrolment schemes to assertive community treatment. It was found that insurance coverage, and contact with mental health and other services can be improved by interventions in this period but the impact on reoffending and reincarceration is complex and interventions may lead to increased return to prison. There is a developing evidence base that suggests targeting this period can improve contact with community mental health and other health services but further high quality evidence with comparable outcomes is needed to provide more definitive conclusions. The impact of programmes on return to prison should be evaluated further to establish the effect of interventions on clinical outcomes and to clarify the role of interventions on reincarceration.