BackgroundEarly intervention in psychosis (EIP) has been developed as an approach to improve the prognosis of people with psychotic disorders and it has been claimed to be a more efficient model of care. However, the evidence is not definitive and doubts have spread regard to the economic outcomes of EIP services amid the usually restricted mental health budget.AimsWe aimed to review the cost-effectiveness evidence of EIP services worldwide.MethodWe systematically reviewed the economic literature about EIP following the Preferred Reporting Items for Systematic reviews and Meta-Analyses statement guidelines. Studies were selected according to previously stated criteria and analysed with standardised critical appraisal tools for trial-based economic evaluations and modelling studies.ResultsA total of 16 studies were selected after applying the eligibility criteria. Most of them were economic evaluations alongside clinical trials. The overall evidence was consistent in the cost-effectiveness of EIP compared with standard care for first episode of psychosis and the Clinical High Risk for Psychosis paradigm. Such evidence was replicated among different health systems, but mainly in high-income countries. The methodological quality of such evidence, however, was moderate and heterogeneity was significant across the studies.ConclusionsThere is consistent evidence that the implementation of EIP services might be a cost-effective alternative across different health systems. Such evidence, nevertheless, derives from heterogeneous and sometimes methodologically flawed studies, reducing the certainty of such statement. More efforts must be done to rigorously assess the value of this intervention, before expanding it among systems where mental health budgets are more constrained.Declaration of interestNone.