The medical internship has sparked recurrent debate on curricular changes currently under way in Brazil. Despite these discussions, an internship model consistent with these changes has still not been established. This essay proposes a framework for the medical internship. We propose that the medical internship be implemented throughout the six years of undergraduate medical training, with primary care as the clinical backbone. This "longitudinal internship" model provides for the gradual introduction to clinical practice beginning with primary care in the first years, adding various outpatient specialty rotations, hospital ward practice, and other practical activities, thereby covering the diversity and complexity of practical experience expected of medical school graduates.