Introduction: Basic life support (BLS) and the use of an automated external defibrillator (AED) improve survival from cardiac arrest. The gold standard for teaching BLS/AED is yet to be identified. The aim of this study was to compare the learning outcome of an instructor-led demonstration with a formal lecture for introducing BLS/AED skills. We hypothesized that a demonstration was superior to a lecture. Methods: First year-medical students were randomised to either a demonstration or a lecture using PowerPoint® Presentation for skill introduction during European Resuscitation Council BLS/AED courses. Participants were skill-tested after training and required to perform all skills correctly to pass the test. Finally, all participants were asked to state their preferred teaching method. Results: Overall, 247 participants were included in the analysis (demonstration group: 124, lecture group: 123). Pass rate was 63% in both groups, p = 1.00. Both groups performed median compression rates within guidelines recommendations, p = 0.09. Mean compression depth was 55 mm (10 mm) in the demonstration group compared with 52 mm (10 mm) in the lecture group, p = 0.05. Median tidal volume was 265 (192, 447) ml and 405 (262, 578) ml, p < 0.001, respectively. The lecture group was 3 s faster at initiating BLS, p < 0.001. In total, 226 (91%) participants preferred demonstration on a manikin for introducing BLS/AED. Conclusion: There was no statistically significant difference in pass rate when comparing a demonstration with a lecture for introducing BLS/AED. The lecture group was slightly faster at initiating BLS. Most participants preferred a demonstration as introduction.