A 47-yr-old man with acute myeloid leukaemia had been in complete remission for 18 months when he developed a gingival tumour. Histological examination revealed leukaemic infiltrate and, at this stage, no other signs of relapse could be demonstrated. Chemotherapy and local radiotherapy resulted in the disappearance of the mass; however, histological abnormalities persisted. First relapse of acute myeloid leukaemia presenting as a gingival tumour has not been previously reported.