A large number of research studies have highlighted the relevance of oral narratives for describing children's linguistic constraints, developmental stages of narrative discourse patterns, and sociocultural identities. Yet, little research has been found on the use of oral narratives as a means to longitudinally improve oral discourse coherence and fluency in English as a Foreign Language (EFL). This article reports a case study which was aimed at exploring and describing oral language enhancement in 26 Chilean preservice teachers of English through the implementation of oral narrative tasks over four months. Oral narrative samples were collected through audio recordings, then transcribed and analyzed through the Narrative Assessment Profile, and analytic rubrics elaborated in light of the literature review carried out for oral fluency. Findings suggest a relation between oral narrative tasks and oral discourse coherence and fluency improvement, with a large effect size (25% for social sciences) on oral discourse coherence. Also, a new measure and dysfluency indicator of L2 oral fluency was discovered and defined as false reformulation. It could be concluded that oral narrative tasks might constitute a valuable instrument for enhancing oral English as a foreign language over time.