Chagas disease (CD) is a protozoan zoonosis caused by Trypanosoma cruzi. Reactivation of CD occurs via drug-induced immunosuppression before and during transplantation. Here, we report the case of a 62-year-old man diagnosed with classic Hodgkin lymphoma who received highly aggressive conditioning chemotherapy before undergoing stem cell transplantation (SCT). The patient tested positive for CD in pre-transplantation evaluation. The patient exhibited persistent fever and elevated C-reactive protein levels before and after SCT, and was treated with antibiotics. Micro-Strout test showed evidence of trypomastigotes and he was treated with benznidazole until tested negative. Post-transplantation seropositive patients should be screened for possible reactivation.