Magnetic resonance provides a non-invasive tool for monitoring normal and leukemic bone marrow. Measurements of the T1 relaxation times are elevated in acute myelogenous leukemia. However, interpatient variability diminishes the usefulness of MR measurements for diagnosing leukemia. In following the time course of individual patients, T1 relaxation time measurements appear to give an early and sensitive indication of leukemic relapse after remission and this may serve a clinical role in the management of leukemia by reducing the regularity of necessary marrow aspirates and biopsies.