The relationship between the Medical College Admission Test (MCAT) score and the amount of undergraduate college training in biology, chemistry, and physics has been investigated. Subjects were medical college candidates who were given the MCAT in October, 1949. They were male, regular full-time students. They attended college in spring and fall of 1949. Almost all were in their junior or senior years. The total number of credits in the three science fields was determined for each student. There were two subgroups; those who had taken a high amount of science courses; and those who had little training. A combined frequency distribution of science credits was made. The principal step was to compare the MCAT Science Test scores of the high and low training groups. Results of the study are presented in tables 1-6. Ability differentials between the pairs of subgroups were taken into account by an analysis of covariance technique. The results of this study are that taking additional science courses beyond a minimal number does not lead to a better score on the MCAT science test. It is not known whether this is due to characteristics of the test or to characteristics of the courses taken or both. The MCAT test probably does not measure advanced knowledge. (SGK).