In this work the Case System of Oromo language is described and explained in the light of the case theory of Chomsky (1981, 1982, 1986a) and its developments by different scholars (cf. Haegeman 1994, Culicover 1997). Chapter One reviews the related literature and briefly introduces the theoretical framework employed in the study. Chapter Two identifies and describes mainly the morphology of Oromo nouns, which is believed to be useful in explaining case system of the language. Chapter Three identifies case assigners and case receivers and it is found out that all the four cases recognized in...