OBJECTIVE To perform a cost-benefits analysis of a clinical pharmacy (CP) service implemented in a Neurology ward of a tertiary teaching hospital. METHODS This is a cost-benefit analysis of a single arm, prospective cohort study performed at the adult Neurology Unit over 36 months, which has evaluated the results of a CP service from a hospital and Public Health System (PHS) perspective. The interventions were classified into 14 categories and the costs identified as direct medical costs. The results were analyzed by the total and marginal cost, the benefit-cost ratio (BCR) and the net benefit (NB). RESULTS The total 334 patients were followed-up and the highest occurrence in 506 interventions was drug introduction (29.0%). The marginal cost for the hospital and avoided cost for PHS was US$182±32 and US$25,536±4,923 per year; and US$0.55 and US$76.4 per patient/year. The BCR and NB were 0.0, -US$26,105 (95%CI -31,850 - -10,610), -US$27,112 (95%CI -33,160-11,720) for the hospital and; 3.0 (95%CI 1.97-4.94), US$51,048 (95%CI 27,645-75,716) and, 4.6 (95%CI 2.24-10.05), US$91,496 (95%CI 34,700-168,050; p < 0.001) for the PHS, both considering adhered and total interventions, respectively. CONCLUSIONS The CP service was not directly cost-benefit at the hospital perspective, but it presented savings for forecast cost related to the occurrence of preventable morbidities, measuring a good cost-benefit for the PHS.