An 11-yr-old girl, who had been treated with human growth hormone (h-GH) for 31 months, developed acute myeloblastic leukemia with an inv(3)(q21q26). Since GH has been suggested to influence the genesis of leukemia, and the inversion 3 has been reported only in adult leukemia patients, the GH treatment may have caused the development of leukemia or accelerated the proliferation of the leukemia cells.