OBJECTIVES: To estimate the budget impact of PP-LAI in treating chronic schizophrenia in Brazil from the perspective of the public payer, specifically for patients with adherence issues. METHODS: The budget impact model (BIM) was used to estimate eligible population and to project investments for the first 5y (2012-2016). An approach based on prevalence and adherence rates reported by previous studies was employed to define the eligible population. Two scenarios were simulated: 1) the current setting, in which schizophrenic patients with adherence issues receive atypical drugs already provided by the Brazilian Public Healthcare System (BPHS) (olanzapine, quetiapine and ziprasidone), and 2) the proposed setting, in which patients presenting non-adherence behaviors on oral atypical therapy can receive PP-LAI. Final costs were calculated considering drug acquisition costs and health resource consumption related to outpatient follow-up, hospitalizations and adverse events. RESULTS: The BIM estimated the population eligible for PP-LAI ranging from 2,207 patients (2012) to 2,271 patients (2016), approximately 0.3% of the projected schizophrenia population attending BPHS services. With all drugs tax exempted, the acquisition costs were: PP-LAI 5,566BRL (1st year) and 4,963BRL (subsequent years); olanzapine 3,850BRL; quetiapine 5,416BRL; ziprasidone 1,474BRL. The model estimated the current BPHS expenses at 287 million BRL in 2012, reaching 296 million BRL in 2016. If PP-LAI is included in the reimbursement list, the yearly budget impact in 2012 would be 2.4 million (+0.83%) and 1.1 million in 2016 (+0.37%). The cumulative budget impact would reach 6,658,573BRL in 5 years. CONCLUSIONS: PP-LAI is an effective therapeutic option for schizophrenic patients, particularly those who would benefit from LAI antipsychotic drugs. In this BIM, the investments to include PP-LAI on BPHS reimbursement lists were estimated to be BRL 6.7 million in five years (an increment of 0.46% in the current budget).