The purpose of this study was to find out the possible effects of pre-versus post-presentation input flooding via reading on simple past tense acquisition among young Iranian EFL learners. Sixty one elementary EFL learners were divided into two experimental and one control group. The experimental groups were exposed to pre and post presentation input flooding via reading while the control group received the traditional method of teaching grammar at a private language institute. A dictogloss activity was also used to check the number of ongoing grammatical errors in all groups. The treatment was conducted in thirty minutes of twelve sessions for about two months. ANCOVA and one way ANOVA results of both post-test and dictogloss indicated the significant effects of pre- and post-presentation input flooding via reading on the acquisition of simple past tense. However, the results of posttest indicated that pre- and post-presentation input flooding groups performed fairly similarly while the results of dictogloss showed the outperformance of the former to the latter.