Water Balance of the Rain-fed Cultural Watersheds in the East   Rungkarn Krishnamra, Ratana Jindapol and Uthai Somsopon   ABSTRACT         During 1989 to 1991, the study of the water balance in agricultural areas of different land-uses in the watersheds of the east were carried out by analyzing rainfall, discharge and evapo-transpiration using Low and Goh's method. Areas of orchard, para- rubber and forest had highly influenced to every factor in the water balance equation.       The study showed that the watersheds in 4 provinces had different water balance equation.The highest average annual rainfall was the watershed in Trad Province, while the lowest was at Chonburi province. Due the important factors in the water balance equation, the watershed in Chonburi province had the highest evapo-transpiration and the lowest at Chanthaburi province. In the whole scenery of 9 watersheds, annual average of runoff and evapo-transpiration were 18.9 and 81.1 percent of annual rainfall.         Keywords : Watershed, Water balance