Background: Chagas-Mazza disease, usually considered a neglected tropical diseases, is an important cause of morbidity and mortality in Latin America. Treatment in adult chronic asymptomatic patients is still in debate. Main limitations of traditional drugs are the adverse drug reactions (ADRs). Nevertheless treatment of young adults and women of childbearing age is proposed to be useful in decreasing progression to cardiovascular disease and mother to child transmission.Our objective is to evaluate tolerance and development of ADRs with benznidazol (BZN) in adult chronic asymptomatic patients with Chagas, in four public medical centers in Ciudad Autónoma de Buenos Aires (CABA), a non-endemic area.Methods & Materials: We conducted a descriptiveobservational study of ADRs related to BZN treatment in four medical centers in CABA from 01/06/2012 to 31/12/2018. Patients between 18 and 65 years, without cardiovascular or digestive disease and Kushnir score of 0-1 were included. Pregnant or breastfeeding women, older than 65 years, or with Kushnir score 2-3 were excluded.Included patients signed an informed consent, were advised on risks-benefits of the medication and prescribed recommendations to improve tolerance. BZN was used at 5 mg/kg dose for 60 days. Daily self-monitoring records and weekly medical controls were performed. Telephone contacts were provided in case of eventualities Results: We included 106 patients (85 female and 21 male) with a median age of 36.7 years (18-60). The ADRs were observed in 56/106 (52.8%) of the patients. Of the total of patients; 80/106 (75.4%) completed the treatment and 26/106 (24.6%) did not complete it. Of those who did not complete, 21/26 presented ADRs, with only 6/21 (28.5%) being suspended at the request of the treating team. Of all the ADRs; 67/79 (84.8%) were mild and 6/106 (5.6%) severe. Only 1 patient (0.9%) required hospitalization and no deaths attributable to ADRs were observed. Conclusion:In our experience, BZD was safe in adults. Tolerance was acceptable and most of the adverse events were gastrointestinal and cutaneous, were mild and could be managed with symptomatic treatment with no mortality observed.