Assessing teaching performance is important for students' learning. Objective: Assess teaching performance in a medical school, using three strategies. Method: 288 Teachers were studied. The three assessment strategies were: students' academic achievement measured with validated exams, teachers' evaluation by students' opinion (2,656 students) with a validated instrument, and a self-assessment tool. Results: There were significant differences (p≤0.001, ANOVA) among the three assessment strategies. Four different teacher categories were obtained using students' opinion. Conclusion: We identified highperformance teachers, those requiring faculty development and those who do not fulfill appropriately their teaching responsibilities.