This study tested the impact of implicit and explicit knowledge of grammar on learners’ use of oral communication strategies (OCSs) and the interface of OCSs and oral fluency. The study was performed on 24 male and 36 female Iranian university students of English Translation studying at Payame Nour Universities of Lar, Khonj, and Evaz chosen based on availability and ease of access. The data were gathered using Timed Grammaticality Judgement Test (Dekeyser, 2000) as a measure of implicit knowledge of grammar, a structure section of TOEFL Paper-based Test (version 2004) as a measure of explicit knowledge of grammar, Oral Communication Strategies Inventory (Nakatani, 2006), and two oral production tasks for measuring learners' oral fluency. Analysis of the data using Multivariate Analysis of Variance (MANOVA) and Pearson’s Correlation showed that both implicit and explicit knowledge of grammar affect learners’ use of oral communication strategies; however, no relationship was found between overall use of OCSs and oral fluency which can be suggestive of greater or possibly overriding impacts of some other variables on oral fluency compared to OCSs. The findings of the study are supposed to provide guidelines for learners, teachers and syllabus designers concerning the use of OCSs, especially with regard to other variables considered in this study.