an individual's beliefs about knowledge and the ways to acquire it, i.e. his/her epistemological beliefs, affect the way to approach the learning process; this has implications in the training of students. it has been suggested that such beliefs are made up by relatively independent dimensions, some related to the nature of knowledge, others to the nature of the learning process. we have inquired into the possible multidimensional nature of epistemological beliefs of medical students, through a likert-type questionnaire, and its possible influence on academic performance in biochemistry as a subject of study. analysis of results showed four dimensions in the measured epistemological beliefs. it was also found that the belief that knowledge is made up of discrete and independent units correlates significantly with poor performance in the mentioned subject.