This paper examines case role in the Urhobo language. Case theory is used as theoretical frame work, the specific objectives is to investigate type of cases and to relate cases roles to argument structures in Urhobo. The study reveals that in the Urhobo language every lexically headed NP must receive case from a case assigner. The Case theory requires that the case assigner govern the NP to which its assigns case. Tense, verb and preposition are case assigners. The infinitive ‘to’ and the passive participles are not case assigners. Case assignment can take place only when the case assigner and the NP to which it assigns case bear a structural relation to one another. It also reveals that irrespective of the theory and its arguments, Urhobo verbs are the basses and centre of its expansion of its constructions. This research also finds out, that the argument structures identified in universal grammar (UG) align with the argument structure of the Urhobo language; the verb assigns arguments to the noun phrases in a sentence. This is traced to the structure of the Urhobo language which is subject-verb-object (SVO). Finally, the study reveals that the function of the nominative case is to mark the subject of the sentence; the vocative is the case of address; the accusative is used to mark the object of a transitive verb; the genitive is the case of possession, ablative case is to mark the instrument with which something is done and the dative case marks the indirect object in the Urhobo language.