On 237 cases of acute leukemia admitted to our clinic from 1953 to 1965, the main symptoms and hematological findings in the initial stage were statistically evaluated. The observation time was devided into 3 periods; I (1953~1957), II (1958~1961) and III (1962~1965). 1) Peripheral blood picture: Severe cases with hemoglobin below 40% (Sahli) were 57.0% during the Ist period and were 28.2% during the IIIrd period. On the other hand mild cases with hemoglobin above 70% were 9.2% during the Ist period and increased to 17.2% during the IIIrd period. Similar tendency was observed on red blood cell count (R. B. C.). Severe cases with R. B. C. below 2×10(6) were found in 66.2% during the Ist period and decreased to 31.0% during the IIIrd period. ...