The Allium tuberosum is a perennial herb. From the ancient time, it has been used for food or medical purpose. Allium tuberosum is widely distributed in Korea, China, Japan and other countries. As herbal medicine, the Allium tuberosum has medical effects on lumbago, sthenia, diuresis, nocturia, hematemesis, anemia, haemorrhoid, hiccups, diarrhea, eczema, sunstroke, pollution and so on. Recently, the Allium tuberosum has been studied on its components, anti-microorganism action, anti-fungal action, anti-arteriosclerosis action, anti-cancer action. However, there has not been any study on hematological effect of allium tuberosum extract on the blood in large dogs whereas the effects of excess garlic and onion on the blood of cattle, horses, dogs, cats and sheep has been reported by many researchers. Thus, this study was performed to observe the hematological effect of excessive Allium tuberosum extract administrated in large dogs. 1. The Red Blood Cell(RBC) count was significantly decreased(p<0.05), Packed Cell Volume (PCV) count were significantly decreased(P<0.05), and Reticulocyte count was significantly increased(p<0.05) 2. The White Blood Cell(WBC) count was significantly increased(p<0.05). 3. The Hemoglobin concentration was significantly decreased(p<0.05) and Mean Corpuscular Hemoglobin Concentration (MCHC) was increased. and Mean Corpuscular Volume(MCV) was significantly increased.(p<0.05). 4. The Reduced glutathione(GSH) and Met-Hemoglobin were significantly increased (p<0.05).