Context: laboratory studies in cognitive psychology with relatively brief final recall intervals suggest that repeated retrieval in the form of tests may result in better retention of information compared with repeated study. Objectives: Our study evaluates if repeated testing of material taught in a real-life educational setting (a didactic conference for paediatric and emergency medicine residents) replicates these findings when measured at a more educationally relevant final recall interval of 6 months. Methods: Residents participated in an interactive teaching session on two topics: (i) status epilepticus, and (ii) myasthenia gravis. Residents were randomised to two counter-balanced groups which either took tests on status epilepticus and studied a review sheet on myasthenia gravis (SE-T/MG-S group) or took tests on myasthenia gravis and studied a review sheet on status epilepticus (MG-T/SE-S group). Testing and studying occurred immediately after teaching and then at two additional times at intervals of about 2 weeks. Residents received feedback after each test. Tests consisted of short-answer questions and the review sheets consisted of information identical to that on the answer sheets for the tests. At about 6 months residents took a final test on both topics. Results: Nineteen residents in the SE-T/MG-S group and 21 residents in the MG-T/SE-S group completed the study. Collapsing across groups, repeated testing produced final test scores that were an average of 13% higher than those produced by repeated study (39% versus 26%) at > 6 months after the initial teaching session (t = 3.93, standard error of the difference = 0.03, P < 0.001, d = 0.91). Conclusions: Repeated testing with feedback appears to result in significantly greater long-term retention of information taught in a didactic conference than repeated, spaced study. Testing should be considered for its potential impact on learning and not only as an assessment device.