After an evaluation has been being administered and scored, it is convenient to analyze each of its items. This procedure gives information about the degree of difficulty determined by the amount of correct answers provided by the student. The degree of difficulty is calculated dividing following number of correct answers by the total number of students. It varies between values close to 0 (when the item is difficult) or to 1 (when it is of low difficulty). We analyzed 8 multiple choice items taken by 99 Physiology course students of the Dentistry School. The degree of difficulty for the items under analysis were: 0.73; 0.46; 0.35; 0.42; 0.53; 0.50; 0.68; 0.83, respectively. The lowest difficulty item was number 8 whereas the most difficult was item number 3. This instrument should be correlated with other didactic elements in order to take decisions.