Non-tuberculous mycobacterial (NTM) disease is a rare cause of neutropenic fever in patients with hematological malignancies. There are few studies on the optimal management for such patients with NTM. We report a case of myelodysplastic syndrome (MDS) treated by umbilical cord blood transplantation (CBT) after Mycobacterium kansasii (M kansasii) pneumonia. A 38-year-old man diagnosed with MDS developed severe pneumonia during induction chemotherapy. Repeated sputum culture uncovered mycobacterium infection. Then, by the polymerase chain reaction of the bronchial lavage fluid, M kansasii infection was proven. After 140 days of anti-NTM therapy, CBT was successfully carried out and the patient recovered without recurrence of NTM infection. This case provides valuable evidence that hematopoietic stem cell transplantation is feasible after a reliable diagnosis and continuous anti-NTM therapy. K E Y W O R D S cord blood transplantation, Mycobacterium kansasii, myelodysplastic syndrome, nontuberculous mycobacterial disease How to cite this article: Yamada A, Akahane D, Katagiri S, et al. Successful cord blood transplantation for myelodysplastic syndrome complicated by Mycobacterium kansasii pneumonia.