The groundvvater budger of tiıe “Niksar Valley” caiculated according to the general bud- get equation, Schoeller (1967). Ali budget elements are caiculated seperately for a period of one year, from October 1986 to September 1987. Wbile the surface and ground water observations were carried out from July 1986 to April 1988. The exposed iithological units are ranged from Paleozoic to Quatemary and, shows different hydrogeoiogical characteristics. The valley fiil materials are from Poliocene to Quaternary. Aguifer parameters are caiculated by permeame- ters, sieve analysis, pumping and înjection tests ete. During the budget period aguifer recieved 2.66 X 10® m3 and diseharged 2.63 x 10® m3 of water.