The triad of diabetes insipidus (DI), monosomy 7, and acute myeloid leukemia in a 7-year-old boy is described. This triad has been described in adults but not in children. The DI ran a transient, self-limiting course and required no specific therapy. The pathogenesis of DI remains unknown, and its transient nature may result in this component of the triad going unnoticed.