RESUMEN
Background: To optimize the teaching-learning process it is fundamental to know the representations that students have regarding knowledge. Epistemological beliefs are implicit theories that guide the practical actions of people. Aim: To characterize and compare epistemological beliefs regarding the nature and acquisition of scientific knowledge of health career students. Material and Methods: Between 2012 and 2013, 726 students coursing first, third or fifth year from six health careers answered a validated questionnaire that includes closed and open questions aimed to characterize their epistemological beliefs about scientific knowledge. Results: Irrespective of the career, when students had to select predefined answers, most of them appeared as constructivists (61%). On the other hand, when they had to argue, the majority seemed objectivist (47%). First-year medical students have the highest frequency of constructivist epistemological beliefs (56%). Paradoxically, the lowest percentage is found (34%) in the fifth year. The students of the health careers, in particular those of Medicine, recognize that knowledge is not acquired immediately (83%) and that its distribution is shared (92%). Conclusions: Discordance between selections and arguments suggests that epistemological sophistication is achieved declaratively but not practically. The lower proportion of students who presented constructivist beliefs in the fifth year compared to first year of Medicine could be associated with the pedagogical approaches used in the different cycles of the career.