OBJECTIVES: Schizophrenic episodes cause socio-economic problems and compliance with therapy is a known problem for schizophrenia patients and their families.The 3-monthly paliperidone palmitate formulation(PP3M) offers long-term benefits for patients by preventing schizophrenic episodes,also reducing the partial compliance risk.This study aims to perform a cost-effectiveness analysis of PP3M in the Turkish healthcare system,using the once-monthly paliperidone palmitate treatment(PP1M) as the comparison agent. METHODS: The cost-of-illness methodology has been used in calculation of the cost data in Turkey.The analysis has been performed retrospectively in a one-year time horizon and from the healthcare payer perspective.Quality-Adjusted Life Year(QALY) caused by the difference in the administration of the two treatments,three-monthly and monthly injections,have been considered as the effectiveness value.American dollars were used as the currency unit based on the purchasing power parity(PPP)($1=1.31TL-OECD 2016). RESULTS: The annual mean cost per schizophrenia patient has been calculated at 6330.2 PPP-$ for treatment with PP1M and at 6006.8 PPP-$ for the treatment with PP3M.For PP1M,drug treatment cost,which consists of antipsychotic drugs used in practice,accounts for 83.7% of the total cost,while outpatient follow-up cost is the second significant cost component at 9.8%.Service and intervention costs comprise 5.7% of the total cost.For PP3M,drug treatment costs,which consist of antipsychotics used in practice,comprises 83.8% of the total cost,while outpatient follow-up cost ranks the second significant cost component at 10.3%.Service and intervention cost accounts for 5.1% of the total cost.Considering the QALY values (0.65-PP1M versus 0.70-PP3M),PP3M treatment has been found to be dominant compared to maintenance therapy with PP1M.(per QALY -6468.0 PPP-$) CONCLUSIONS: PP3M addresses unmet needs expected by new treatments due to several positive characteristics such as reduction of the treatment discontinuation risk,prevention of relapses,reduction in Healthcare Resource Use related to hospitalization.Therefore,PP3M has been determined to be cost-saving health technology by lowering the costs of hospitalization,drug treatment,adverse event and outpatient clinic,compared to maintenance schizophrenia therapy with PP1M.