Abstract The present study aims at investigating effects of planned mother tongue on students’ performance of speaking. A quasi-experimental design was employed to test the hypothesis that using mother tongue in a planned way in to EFL classrooms would enhance students’ speaking performance. Since the design of the study is Quasi-experimental, a non- probable sampling technique of purposive sampling was used to select the participants of the study, two intact groups that comprised 80 students were selected and participated in the study. Grade 11 ‘K’ Students (n=40) were assigned as experimental group and grade 11’H’ students (n=40) were assigned as a control group by Lottery Method. The researcher used tests and un-structured interview as a relevant data gathering tools. A mother tongue based language teaching manual was prepared by the researcher considering the criteria of Nunan (1991) . The participants’ speaking performance was stable before the treatment was given for the experimental group. A pre-test was administered for both the control and experimental group to see the similarity and the difference between the control and experimental group speaking performance. Students’ score in the pretest witnessed that the two groups were nearly similar in speaking performance. Then, treatment was given for the experimental group for two months by the extra class .The experimental group was taught through the intervention of mother tongue whereas the control group was taught without mother tongue intervention. At the end, post-test was administered to gauge effects of mother tongue /Amharic/on improving the speaking performance of the learners. The data from the two tests were analyzed quantitatively through statistical techniques of independent sample ttest and paired sample t-test. The results of the study showed that, there was a statistically significant improvement mainly on the three aspects of speaking (grammar, pronunciation and vocabulary) and the overall speaking performance of the students following the speaking sessions in eight weeks /intervention/ .From this we could conclude that judicious/well planed/ use of mother tongue for ambiguous instructions, difficult concepts and words had a significant effect on promoting the students’ speaking performance than teaching speaking without the use of mother tongue. Based on the results, the alternative hypothesis which was stated as, ‘There will be statistically significance difference among the mean score of the two groups due to the intervention of mother tongue’’ was accepted whilst the null hypothesis was rejected. The data gathered from the unstructured interview was analyzed qualitatively and confirm that the use of planned mother tongue in EFL speaking classroom was perceived as an effective technique in encouraging and motivating students to speak or use the target language in their classroom. For pedagogical practice, the results of this study indicate that the use of appropriate level of mother tongue for much complex ideas in to EFL classroom may indeed produce positive output. Over all, such results might show the positive potential of mother tongue use on students’ performance to speak the target language.