The purpose of this study was to compare traditional lecture-based (LB) and case-based/problem-based (CB/PB) learning in a large group. Year 3 veterinary students at Kansas State University were asked to participate in a randomized controlled study. Students were grouped and randomly assigned to be taught by a CB/PB or a LB method. Students took identical multiple-choice examinations, one given within a week of the last class and a different one given four months later. There was no direct effect of teaching method on group scores for either examination. CB/PB students scored higher on higher-difficulty questions on the first examination (p < 0.003), but there was no effect on questions of lower and medium difficulty. There was no effect of teaching method on student performance for the second examination; however, the question difficulty category scores were all different (p < 0.017). Evaluation of examination scores suggests that the two teaching methods were of similar efficacy.