Background: Teaching of clinical reasoning (CR) can be facilitated by educational strategies guided by illness script theory. Objective: To evaluate the effects of an educational strategy guided by illness script theory on the diagnostic accuracy of chest pain in medical students. Methods: Experimental study in 3 phases, with 18 third-year medical students completing phase 3. Phases 1 and 2 had 27 students. In phase 1, each participant solved 8 clinical cases (6 of chest pain and 2 distractors). In phase 2, participants were divided into 2 groups, which distinctly trained 3 of the chest pain diagnoses from phase 1. In phase 3, after 1 week, each participant solved 8 new cases, with the same diagnoses as phase 1. Case resolution time and diagnostic accuracy were evaluated. The significance level adopted for statistical analysis was p < 0.05. Results: In phase 3, both groups showed improved diagnostic accuracy and reduced case resolution time for the trained diagnoses, with no transfer of learning. For these diagnoses, the diagnostic accuracy scores in phases 1 and 3 were: group 1 = 1.00, IQR [0.00 to 1.001 versus 2.00, IQR [2.00 to 2.501, p = 0.017 and group 2 = 1.00, IQR [0.66 to 1.171 versus 3.00, IQR [1.33 to 3.001, p = 0.006. Case resolution times in seconds were: group 1: 485, IQR [450 to 5831 versus 318, IQR [284 to 4181, p = 0.027 and group 2: 655, IQR [543 to 7401 versus 408, IQR [337 to 5691, p = 0.010. Conclusion: The proposed strategy seems to contribute to improved diagnostic accuracy, and it may be considered for teaching CR.