The antiparasitic activity of allopurinol, against Trypanosoma cruzi, was evaluated by a procedure using infected triatomines. This methodology indicated that the drug was unable to eliminate the protozoa in the digestive tract of the insects. Therefore, further knowledge to improve our understanding of allopurinol in the context of the etiologic treatment of infection by T. cruzi was not acquired. Despite this finding the drug continues to be used, even though its performance appears to be full of divergences and contradictions.