Summary.Account of 24 cases of acute leukemia in children.The acute leukemia in children as a rule is a myeloblast‐leuke‐mia (in at least 21 of 24 cases).The initial symptoms are diffuse, – fatigue, fever, lack of appetite and pallor. In most cases (23 of 24) there is found either splenic or glandular enlargement and besides, in 13 cases also enlargement of the liver. These symptoms are considered as specially valuable in an early diagnosis.3/4 of the cases commence in the first 5 years of life.Anemia is a frequent symptom in an early stage of the disease, but in some cases it may be absent for weeks.The red blood corpuscles show no characteristics. Index varies between 0.7 and 1.8. In 20 out of 23 cases index lies between 0.8 and 1.2.Clinical bleeding‐tendency is found in 50 % of the patients in the more advanced stages of the disease. No connection between the bleeding‐tendency and the number of thrombocytes has been demonstrated.The number of white blood cells varies within wide limits, from 1300 to 185 000 per mm3of blood. It also varies highly from time to time in the individual patient. On admission to the department, 21 of 24 patients show values below 20 000 white blood cells per mm3of blood, 17 below 10 000. 2 patients showed above 30 000 white blood cells per mm3of blood.Eoentgen picture of the bones have been taken in 17 patients. 5 show certain changes similar to those that sometimes are found in acute leukemia.In 18 cases it has been made successful sternal puncture with findings of bone marrow rich in cells, with up to 99.4 % of myeloblasts. The pathological cellular type has in all cases been demonstrated in blood‐smear preparations, in 17 of 18 cases however, they have been recognised as myeloblasts only after successful sternal puncture having ascertained th