Although considerable research has been done on the blood picture of the horse, hot-blooded and cold-blooded, little work has been made of the blood picture of the army pack horse, Jeju horse. The object of the present investigation was to make good this deficiency, and to suggest standard for the blood picture of army pack horses kept under the regular military training and the ideal feeding in the heart of a mountain. Blood samples were drawn from the jugular vein through a 15-gauge bleeding needle from 41 males and 28 females, aging 3 to 9 years old. It was taken between seven and nine o'clock in the morning. Animals were handled as quietly as possible to avoid any excitation. No restraint other than a halter was used. Enumeration of erythrocyte, total and differential leukocyte count, determination of hemoglobin in blood, and the value of packed cell volume were male in the usual manner, and erythrocytic constant was calculated by the method of Wintrobe. Erythrocyte count was $7.83{\pm}0.20(4.95{\sim}11.05){\times}10^6/mm^3$(SE). This value was much lower than hot-horses, but slightly higer than the values of cold-horse reported from foreign country. Concentration of hemoglobin in blood was $13.0{\pm}0.33(9.5{\sim}17.8)g/100ml$. This value was much higher than that of cold-horses observed by the other authors, approaching to the values of hot-horses. Packed cell volume was $32.1{\pm}0.92(22{\sim}42)ml/100ml$. This vague was a little higher than that of the other cold-horses. Mean corpuscular volume was $41.5{\pm}1.20(26.6{\sim}59.3){\mu}m^3$. This value matched so well with the other results recorded by various investigators. Mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration were $16.9{\pm}0.43(12.3{\sim}25)$ pg and $41.0{\pm}0.45(29.1{\sim}51.1)g/100ml$, respectively. These values were significantly higher than the values found by the other investigations. Total leukocyte enumeration was $10.5{\pm}0.41(5.6{\sim}17.9){\times}10^3/mm^3$, being considered as normal. And differential leukocyte count of neutrophil was $44.5{\pm}2.23(15{\sim}76)%$, $5,527{\pm}234(2,231{\sim}9,144)/mm^3$, of lymphocyte $50.5{\pm}1.19(19{\sim}77)%$, $4,307{\pm}125(1,456{\sim}11,098)/mm^3$, of monocytel (0~4)%, $105(0{\sim}352)/mm^3$, of eosiophil 3.2(0~14)%, $340(0{\sim}1,232)/mm^3$ and of basophil 0.25(0~3)%, $23(0{\sim}236)/mm^3$. The percentage of the differential count obtained from the present work showed a good agreement with the results of various authors. Of the horses examined monocyte was found from 42 horses, eosinophil from 62 horses and basophil from 10 horses. No significant differences recognized between male and female horses, and the effect of age was not observed between three to nine years old. Judging from the blood picture of the present investigation, it could be stated that the army pack horses on training were kept better than the average farming conditions.