The present research paper tries to discover the effect of teachers' oral corrective feedback (OCF) on EFL learners' speaking skills (grammar, vocabulary, pronunciation, and fluency). The study relies on the use of an experimental design and direct observations. 20 participants formed the experimental group. All subjects are intermediate foreign language learners of English (EFL). They are given an initial pre-test. Then, this experimental group undergoes intensive oral corrective feedback (mainly through prompts, recasts and explicit correction) delivered by their teacher during various oral activities. Finally, a post-test is applied. The analysis of the pre-test and post-test scores of the experimental group both quantitavely and qualitatively (using the MELA-Scoring Matrix) and the calculation of the mean rate of errors pre 100 words shows that learners' progress in oral performances vary from one individual to another. The findings of this study reveal that immediate and explicit OCF was able to positively affect EFL learners' grammatical development; yet, it was not helpful to ameliorate the learners' utterances in terms of vocabulary, fluency and pronunciation.