Observations were made on the blood picture of total 196 heads of healthy Korean cattles, including 98 males and 98 females in the purpose of determination of hematological values and its sex difference, and seasonal variations during one year period from December 1963 to November 1964. The blood sampling were scheduled by random in four different seasons and the sample size of both sex included in each season were designated to be same size. The ranges, averages or mean values of the erythrocytes, hemoglobin, hematocrit, mean corpuscular hemoglobin concentration, total white blood cell count and differential count were determined in this studies and their respective standard deviation, standard error of means, sex defferences and seasonal variations were as follows; 1. The erythrocyte count of male showed a range of $5.0{\times}10^6/c.mm$ to $8.75{\times}10^6/c.mm$ with a mean of $6.5{\pm}0.096{\times}10^6/c.mm$. Female showed a range of $5.0{\times}10^6/c.mm$ to $8.30{\times}10^6/c.mm$, with a mean of 6. $131{\pm}0.078{\times}10^6/c.mm$. There was a highly significant sex difference and seasomal variation was not found to be significant. 2. The hemoglobin value of male showed a range of 9.0g/100cc. to 14.5g/100cc. with a mean of $11.074{\pm}0.143g/100cc$. Female showed a range of 9.0g/100cc to 13.0g/100cc. with a mean of $10.745{\pm}0.034g/100cc$. There was a highly significant sex difference and seasonal variation was not found to be significant. 3. The hematocrit value of male showed a range of 28% to 45% and with a mean of $34.867{\pm}0.468%$. Female showed a range of 28% to 42% with a mean of $32.888{\pm}0.322%$. There was a highly significant sex difference and seasonal variation was not found to be significant. 4. The mean corpuscular hemoglobin of male showed a range of 14.4rr. to 19.6rr. with a mean of $17.1{\pm}0.112rr$. Female showed a range of 14.7rr. to 19.5rr. with a mean of $17.6{\pm}0.113rr$. 5. The mean corpusular volume of male showed a range of $42.5{\mu}^3$ to $62.2{\mu}^3$ with a mean of $53.9{\pm}0.419{\mu}^3$, Female showed a range of $44.2{\mu}^3$ to $60.0{\mu}^3$ with a mean of $53.8{\pm}0.375{\mu}^3$. 6. The mean corpuscular hemoglobin concentration of male showed a range of 28.1 % to 34.9% with a mean of $31.4{\pm}0.161%$. Female showed a range of 28.0% to 34.9% with a mean of $30.9{\pm}0.169%$. 7. The total leucocyte count of male showed a range of 4,000/c.mm to 13,100/c.mm. with a mean of $9,338{\pm}218.23/c.mm$. Female showed a range of 4,000/c.mm. to 14,000/c.mm. with a mean of $9,338{\pm}235.90/c.mm$. Six difference was not found to be significant and there was a highly significant seasonal variation. 8. The differential count of male, the means of neutrophil, stab, segmented cell, Iymphocyte, monocyte, eosinophil and basophil were $31.173{\pm}0.570%$, 0.3%. $30.867{\pm}0.564%$, $55.112{\pm}0.603%$, $3.745{\pm}0.082%$, $9.867{\pm}0.422%$ and 0.14% rspectively. Female showed means of $31.010{\pm}0.572%$, 0.2%, $30.806{\pm}0.569%$, $53.929{\pm}0.634%$, $4.082{\pm}0.109%$, $10.908{\pm}0.503%$ and 0.12% respectively. There were significant sex differences in monocyte and highly significant sex difference in eosinophil, and seasonal variation were found to be highly significant in neutrophil, monocyte and eosinophil. 9. Hematological comparison made between cattles infested with so called "small type piroplasma" and non-infested group. The result of investigation showed no significant difference upon the red blood cell, hemoglobin and hematocrit values between lighty infested group and non-infested group. 10. Age distribution of test group in this study ranged from 2 years to 6 years in both sex and their average age were $4.45{\pm}0.114$(male) and $4.50{\pm}0.116$(female). There found to be no significant sex difference and seasonal variations in the age of test group.