Modern management of rectal cancer highly depends on the interpretation of high-spatial-resolution MRI, which determines the benefits from preoperative chemoradiotherapy or surgery alone. Accordingly, the baseline MRI report plays a pivotal role in planning the treatment. Although several structured reporting templates for rectal cancer staging on MRI are available, many radiologists still use the free-text format. In this review, we discuss the essential items for reporting rectal cancer on MRI before treatment to guide general radiologists in preparing a qualified report.