In a study conducted to see which method of error treatment was more effective in EFL writing classes, 288 Iranian EFL learners took the TOEFL test to be grouped in two homogeneous classes. Each student in each group wrote a paragraph on a general topic which was proofread for mistakes/errors by three experienced EFL writing teachers (i.e., Pretest). One group received Red Pen treatment (RPM) and the other Remedial Instruction treatment (RIM). After a two-week interval, both groups repeated the same writing assignment proofread by the same teachers (Post-test). A Mixed Between-Within Subjects Analysis of Variance (SPANOVA) was conducted to analyze the effect of two different types of treatment (i.e., RPM, and RIM). Results, after analysis of the data, indicated that the main effect was significant for time but not for group. It was further noticed that the interaction effect was also significant. The RPM method, although not statistically significant, was slightly more effective in enhancing EFL written performance than the RIM method.