Residents serve as medical students' primary teachers for practical clinical skills. The purpose of this study is to provide an updated systematic review of the literature on residents-as-teachers curricula to determine the most evidence-based curricula and evaluation strategy. In 2008, the authors performed a systematic review of the literature with PubMed using the MESH terms "internship and residency" and "teaching," as well as a key word search of the term "residents as teachers." The search was limited to publications in English from 1975 to 2008. A total of 24 studies met inclusion criteria. Eleven (45.8%) were uncontrolled studies, seven (29.2%) were randomized control trials, and six (25%) were nonrandomized controlled trials. The mean sample size of all studies was 39.6. Evaluation was performed by a variety of means including objective structured teaching exams (5; 20.8%), videotape evaluations (6; 25.0%), learner evaluations (11; 45.8%), and self-questionnaires (7; 29.2%). The mean intervention length was 7.6 hours, and the most common intervention was based on the One-Minute Preceptor. Research on residents-as-teachers curricula is limited by both the number of studies and their methodology. Despite this, the results demonstrated that residents-as-teachers curricula can significantly improve residents' teaching skills. In addition, the studies' methodologies have improved over time. Using these data, the authors recommend an evidence-based intervention and evaluation, which would include a three-hours-or-longer intervention (and, if possible, periodic reinforcement) based on the One-Minute Preceptor. The evaluation should be a randomized controlled trial using an objective structured teaching examination.