Factors Effected on Hydrological Characteristics of Rainfed Agricultural Watersheds in the East   Ratana Jindapol, Rungkarn Krishnamra, Somjit Khumnol and Uthai Somsopon   ABSTRACT         The watershed characteristics were studied for factors effecting on streamflow quantity in Thailand by observation trial method in terms of drainage area (A), axial length (L), average width (W), form factor (F), compactness coefficient (Kc), average inclination (Si), slope of the releif (Sr), stream slope (St), maximum elevation-minimum elevation (E), soil hydrologic capacity represented by percent of moisture freely drained by gravity (G), and annual rainfall and streamflow recorded during 1988 to 1991. Three selected small watershed namely : Huai Kao Pai 1, Huai Pun Sadet 1 and Huai Kao Kae Lae 1 which stepwise regression analysis indicated that the amount of annual rainfall plays most essential role in predicting annual streamflow quantity followed by stream slope, soil hydrologic capacity, form factor and drainage area respectively.       Although the multiple R2 was increased by adding some parameters in equation but streamflow prediction accuracy was decreased. So the regression equation for predicting annual streamflow quantity for any small agricultural watershed in Eastern Thailand is Q=1962.3672 + .8842 R (r2 = 0.81)         Keywords : Hydrological, Watershed