Background: Spain has the second highest number of Chagas disease-infected patients among non-endemic countries. However, there is limited knowledge about pharmacist involvement in managing patients with Chagas disease. Method: A retrospective observational study was performed in two periods (before and after intervention) to describe the characteristics of patients with Chagas disease. Pharmacist intervention, based on two pharmacist-visit programs and development of information for patients, was applied to patients under pharmacological treatment in a non-endemic country. Depending on the initial results in 2010e2011, specific pharmacist attention program for patients with Chagas disease was implemented in 2012. The results of 2010e2011 (before intervention) and 2013 (after intervention) were compared. Results: A high number of adverse drug reactions were reported in both periods, 50.0% (2010e2011) vs. 90.9% (2013). With regard to treatment completion, in 2010e2011, 60% achieved the treatment completion criteria (>95% days of treatment) vs. 68.2% in 2013 (p Z 0.580). There was, however, a significant increase in the detection of ADRs in the second period (50.0% vs. 90.9%; p Z 0.003) and an increase in the severity (75% [6/8] of uncompleted treatments were due to ADRs vs. 100% [7/7] in the first and second period, respectively).