The 2016 undergraduate medical degree curriculum at the Facultad de Estudios Superiores Iztacala of the Universidad Nacional Autónoma de México (UNAM) is presented. It is the result of a long institutional reflection and academic dialog process of approximately three years, which culminated in its approval by UNAM's Academic Council for the Biology, Chemistry, and Health Sciences areas on January 25, 2016. Its most relevant characteristics are: modular organization, four knowledge areas (biomedical, methodological, socio-psychological, and humanistic and medical practice), and new modules such as Seminar of socio-psycho-biological integration; Genetics and molecular biology; Biochemistry and cellular biology; Pharmacological basis of therapeutics; Infectious diseases, microbiology and parasitology; Medical ethics; Public health; and Evidence-based medicine - clinical epidemiology. To achieve a more flexible curriculum, optional modules were included. To make possible the curricular change, improving the teaching strategies, innovating the learning assessment methods, supporting the training and updating of the teaching staff, and establishing a curriculum development committee for following up and evaluating the program, are necessary. Curricular changes are difficult and complex processes; they suppose challenges and opportunities. It is mandatory to plan them carefully and sensitively to allow a successful transition and avoid conflicts for the students, the teachers and the institution.