Leukemic lung lesions are complex and various. The authors studied the clinicopathologic changes in 104 autopsied leukemic cases collected from 1953 to 1990. 22.1% of the cases had the symptoms of respiratory tract admission and 40.4% developed the symptoms before death. 12.8% of the patients were diagnosed with X-ray to have tuberculosis and infections on admission and 42% cases have these changes in the terminal phase. The main pathological changes are pleural effusion, pleural adhesion, intrapulmonary infections, hemorrhage and Myleran lung. The rate of leukemic cell infiltration in lungs was 96.2% and the infiltration was mainly interstitial. Intravascular leukemic cell stasis was found in 91.3% of the cases. The pathological changes in each case were usually multiple and 84.6% of the cases had more than two kinds of changes. We compared the X-ray diagnoses with pathological ones and it was shown that complete coincidence was present only in 2.9%, partial coincidence in 58.8% and no coincidence in 38.3% of the cases.