This study investigated the immediate and delayed effects of error correction on the accuracy improvement of intermediate EFL learners’ writing. Through TOEFL test, the researcher selected 3 intact intermediate classes and assigned them into peer correction, self-correction and teacher correction groups. Before the main treatment, all participants were requested to write a composition on a topic, which served the purpose of pre-test. After writing the composition, the first group (peer), including two learners in each group, corrected the errors underlined by the teacher together. The learners in the second group, namely, self-correction, corrected the errors underlined by teacher individually and the third group received the correct forms written by the teacher on top of the errors. All the groups wrote 6 compositions on the topics during 6 sessions. The first topic served the purpose of immediate pre-test. This procedure was followed for 6 weeks and the 6th composition was regarded as immediate post-test and after a month (12th week), delayed post-test was conducted for all learners. The findings of ANOVA indicated that both peer correction and selfcorrection were influential in enhancing learners' writing accuracy; however, the group doing peer correction outperformed the self-correction one.