Allogeneic haematopoietic stem cell transplantation (allo-HSCT) is the only cure for juvenile myelomonocytic leukaemia (JMML), but relapse remains the major cause of failure. A second transplant may be considered a way to induce the graft vs. leukaemia effect in patients who relapse after their first HSCT. We describe a 7-month-old girl with JMML who relapsed after a first, related allo-HSCT, and who again relapsed 8 months after the second transplant, despite discontinuation of immusuppressive therapy. She underwent a third allogeneic transplant from another related donor. At the time of this report the patient is in complete remission 26 months after the third transplant. We suggest that a third allo-HSCT may be taken into consideration for JMML patients who experience relapse, even after two previous transplants.