Since Dock and Warthin (1), in 1904, first summarized the 21 cases of chloroma which they had collected from 1893 until that time, there have been several more complete reviews of the literature (2–5). At present no one doubts the relationship of this condition to leukemia, the only controversial point lying in the differentiation of the lymphoid and myelogenous groups. Washburn (5), who reviewed the literature from 1823 to 1929, collected only 162 authentic cases of chloroma. From that date to September 1935, 35 additional cases have been reported. The majority of these have fallen into the myelogenous group, but no accurate estimate can be made because of the difficulty of distinguishing the two types. In all but two instances (5–6), the disease has been fatal. Case Report A woman, aged thirty years, was admitted to the service of Dr. Albert Cook, Dec. 20, 1935, because of pain in the left flank of five weeks' duration. The family and past histories were not significant, the patient never having been seriously ill. She was married and had two children living and well. About six weeks prior to admission she suffered a severe “cold,” following which she began to have pain in the left flank and lumbar region, which became progressively worse. Because of this, hospitalization was advised. There were no other complaints. The patient was obese and extremely pale. No abnormal clinical findings were observed referable to either the heart or the lungs. No palpable masses were present in the abdomen, but there was costovertebral tenderness in the left lumbar region on heavy percussion. Urinalysis was negative. The temperature was 101° F.; pulse 110; respirations 23. A routine blood count was done on admission (see Table 1) and a diagnosis of acute myeloblastic leukemia with possible renal calculus was made. Flat plates of the kidneys and retrograde pyelography revealed normal kidneys and good function on both sides. Urine from each kidney was negative.