This is a morphosyntactic analysis of Dholuo verb system in Chomsky's (2008) Derivation by Phase theory of syntax. Dholuo is a member of the Western Nilotic group in the larger Nilo-Saharan language family. The study is an attempt to account for the various aspect of Dholuo verb system in a probe-goal relationship and feature interpretability and feature checking approach to syntactic analysis. The study focuses on how periphrastic elements are integrated in the Dholuo verb system. It also investigates case assignment, passive and antipassive constructions and the benefactive applicative in Dholuo verb system in the proposed theoretical framework. The research findings show that Derivation by Phase theory cannot fully account for the linguistic variations of the Dholuo verb system without modification to the theory.