The water celery, Oenanthe javanica DC., is widely distributed in Korea and the other South East Asian countries. From ancient times, the water celery has widely been used for food or medicine. In herbal medicine, the water celery has a medical actions which are defervescence, diuresis, hypotensor, appetizer. Recently, studies on the water celery are briskly being conducted. For example, studies on the morphologic property and classifications of origin of the water celery, studies on the chemical constituents of the Water celery, studies on the bio activities of the water celery which contains flavonoids. However, there is not studies of hematological changes in dogs administrated the water celery until now. Consicontly, this study was conducted to observe the hematological changes in dogs administrated excessive amount of the water celery concentrated extract for a long period. In this studies, all dogs showed significantly decrease of the RBC, PCV, Hb and MCHC, and increase of the WBC, MCV, GSH and reticulocytes, but did not significantly change in the Met-Hb.