In this paper critical reading is considered as the key method for the construction of knowledge. Its characteristics are analyzed in detail and some implications in medical education are emphasized. The outstanding characteristics of critical reading is the ability of the reader to selectively assimilate the information in the text. Criticism is contrary to the reductionist approaches in which the real world is atomized in disjointed compartments. We emphasize the main components of critical reading: a) a passion for knowledge; b) an autocritical attitude; c) a transdisciplinary vision; d) the development of a personal point of view; e) an aperture towards new knowledge; and f) an adequate social environment.