Giant cell myocarditis (GCM) is a very aggressive form of myocardial inflammation. While immunosuppressive therapy is usually able to keep under control the disease and prolong the average transplant-free survival in many patients, effective therapeutic strategies to prevent or treat the recurrence of GCM in transplanted organs are still to be defined. We report the case of a young woman with idiopathic GCM who, despite immediate aggressive immunosuppressive therapy, rapidly progressed to irreversible heart failure and required urgent heart transplantation. Yet, 2 months later, the disease recurred in the transplanted heart, despite an intensive four-drug antirejection regimen. The introduction of rituximab, an anti-CD20 monoclonal antibody, 375 mg/m2/week i.v. for four consecutive weeks and then every 4 months as maintenance therapy, determined a complete and steady clinical remission of the disease. After nineteen months since rituximab administration, the patient is doing well and repeated follow-up endo-myocardial biopsies confirmed the complete resolution of myocardial inflammation. Our experience seems to suggest that rituximab can be a reasonably effective and safe therapeutic option in GCM recurring in transplanted organs.