A phase 2 clinical trial to evaluate the the efficacy of different benznidazole regimens (300mg/day for 60 days, 150mg/day for 60 days, and 400mg/day for 15 days) for the treatment of chronic Chagas disease in adult patients. The efficacy is assessed through the proportion of patients with negative parasitaemia measured by Polymerase Chain Reaction (PCR) during the first 12 months after starting treatment. The study will be performed in Spain, Brazil, Argentina and Colombia.

Inclusion Criteria:

• Over 18 years old.
• Diagnosis of Chagas disease through two different serological tests.
• Positive T. cruzi PCR in peripheral blood.
• Signed informed consent.

Exclusion Criteria:

• Previous treatment with Benznidazole or Nifurtimox.
• Alcohol consumption.
• Acute or chronic health problems that could interfere in the assessment of the efficacy or safety of the drug (acute infections, HIV infection, liver or renal impairment, etc).
• Nitroimidazole hipersensitivity.
• Concomitant or previous treatment with allopurinol or antifungal drugs.
• Pregnancy.