The objectives of the study were to determine the cost variability of antipsychotics in public (hospitals) and private pharmaceutical establishments (pharmacies and clinics), calculate the cost variability of antipsychotics between establishments and estimate the cost of monthly maintenance treatment with antipsychotics. A cost analysis study was performed, unit costs of antipsychotics were obtained from the Peruvian Pharmaceutical Products Observatory. The results show that the cost variability of an-tipsychotics was greater in pharmacies and clinics than in hospitals, and the analysis of cost variability between pharmaceutical establishments showed that the cost of an antipsychotic in a pharmacy and clinic was 1.3 to 140 times and 2.8 to 124 times, respectively, the cost of the drug in a hospital. The cost of monthly maintenance treatment varied from S/ 3 to S/ 2130 according to the drug and pharmaceutical establishment.