Antimicrobial stewardship program (AMSP) promotes the rational use of the antimicrobial, ensuring that each patient receives the correct antibiotic, by the correct time and at the correct dose.To establish the association of the results of an AMSP led by a pharmaceutical chemist, in terms of antibiotic consumption, duration of treatment and costs in a tertiary healthcare setting.Ambispective cohort study. In the exposed cohort, in the environment of a AMSP, a pharmacist with training in infectious diseases evaluated and intervened the indication, dosage, duration of treatment and bacterial spectrum of the antimicrobial. The no-exposed cohort corresponded to a retrospective population that was similar (paired) to the exposed cohort, but that did not receive an evaluation of its antimicrobial therapy.258 patients were identified in the exposed cohort and 247 in the cohort not exposed to the AMSP. Decrease in the consumption of antibiotics was observed (119,831 vs 137,678 DDD/100 patients-day, p < 0.001) and a decrease in 34.1% of the costs associated with antibiotic therapy of the exposed cohort, in comparison with the cohort not exposed to the AMSP.AMSP led by a pharmacist have better outcomes in terms of consumption and lower costs associated with antibiotic therapy.