Myelofibrosis is a rare hematopoietic stem cell neoplasm leading to marked bone marrow fibrosis and ineffective hematopoiesis. We report a case highlighting the potential role of ¹⁸F fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for therapy monitoring. A 62-year-old man with myelofibrosis underwent FDG-PET/CT for evaluation of the extent of disease before and after allogeneic stem cell transplantation (SCT). PET after SCT demonstrated complete normalization of initially increased bone marrow tracer uptake, consistent with bone marrow biopsy showing complete remission. ¹⁸F-FDG-PET/CT may become a valuable diagnostic tool in myelofibrosis, enabling both sensitive initial staging and therapy monitoring.