OBJECTIVES: The inadequate use of antibiotics may result in adverse events, antimicrobial resistance and excess costs. Economic assessments of antibiotic use are limited in low- and middle-income countries. This study aims to estimate the overall cost of antibiotic use and specific costs of antibiotic resistant infection or adverse drug reaction in a hospital of the Dominican Republic. METHODS: We collected data on adult patients admitted to the Hospital General Plaza de la Salud, Santo Domingo, from 01/09/2013 to 30/06/2014. For each patient treated with antibiotics, we estimated the daily cost of hospitalization. This cost includes the antibiotic treatment, pharmacy management, healthcare services, and bed occupancy. We also evaluated the additional cost for patients that developed an antibiotic resistant infection or an adverse drug reaction. RESULTS: N=6,343 adult inpatients were included. The mean daily cost of hospitalization was 70.21 USD per patient treated with antibiotics. The average length of stay was 4.62 days and the mean cost for the whole hospitalization period was 388.72 USD. The cost was allocated as follows: 27.73% antibiotic treatment, 4.67% pharmacy management, 5.66% healthcare services, 61.94% bed occupancy. Sixty patients presented adverse drug reactions (n=9, mean of 2.71 extra days of stay; 124.51 USD for additional hospitalization) or hospital-acquired infections due to resistant bacteria (n=51, mean of 16.84 extra days of stay; 2,643.44 USD for additional hospitalization). The total additional cost in patients with an adverse event related to antibiotic use was 135,936.01 USD. CONCLUSIONS: A better use of antibiotics would not only contribute to patient safety, by decreasing hospital infections due to resistant bacteria and adverse reactions, but also to financial savings. This study was of main importance to improve antibiotic policy in the Dominican Republic, where both the investigated hospital and national authorities have implemented restrictive programs for the control of antibiotic use within hospital settings.