Background: A key challenge clinicians face when considering differential diagnoses is whether the patient data have been adequately collected. Insufficient data may inadvertently lead to premature closure of the diagnostic process. This study aimed to test the hypothesis that the application of a mnemonic checklist helps to stimulate more patient data collection, thus leading to better diagnostic consideration. Methods: A total of 88 final year medical students were assigned to either an educational intervention group or a control group in a non-equivalent group post-test only design. Participants in the intervention group received a tutorial on the use of a mnemonic checklist aimed to minimize cognitive errors in clinical decision-making. Two weeks later, the participants in both groups were given a script concordance test consisting of 10 cases, with 3 items per case, to assess their clinical decisions when additional data are given in the case scenarios. Results: The Mann-Whitney U-test performed on the total scores from both groups showed no statistical significance (U = 792, z = -1.408, p = 0.159). When comparisons were made for the first half and the second half of the SCT, it was found that participants in the intervention group performed significantly better than participants in the control group in the first half of the test, with median scores of 9.15 (IQR 8.00-10.28) vs. 8.18 (IQR 7.16-9.24) respectively, U = 642.5, z = -2.661, p = 0.008. No significant difference was found in the second half of the test, with the median score of 9.58 (IQR 8.90-10.56) vs. 9.81 (IQR 8.83-11.12) for the intervention group and control group respectively (U = 897.5, z = -0.524, p = 0.60). Conclusion: Checklist use in differential diagnoses consideration did show some benefit. However, this benefit seems to have been traded off by the time and effort in using it. More research is needed to determine whether this benefit could be translated into clinical practice after repetitive use.