The polymerase chain reaction (PCR) was usedto evaluate the course of treatment of an acutely infected patient with Trypanosoma cruzi. The reactions were performed using a primer pair (TCZ1 and TCZ2) which prime the amplification of a highly repetive 195-bp T. cruzi genomic DNA. Treatment with benzonidazole (5 mg/kg boby weight) was strarted when parsitemia was 140 parsites per ml of blood. The strong DNA amplification bands initially observed were no longer detected after 8 days following treatment