Introduction Clinical reasoning is often not explicitly taught to novice medical students. Pre-clerkship clinical skills courses are an ideal venue to teach the clinical reasoning process. The aim of the study was to evaluate the impact of a preclinical clinical reasoning curriculum through an end-of-semester objective structured clinical examination.

Methods This study was conducted through our longitudinal clinical skills course.

Second year medical (M2) students who received the clinical reasoning curriculum in 2018 formed the study cohort. M2 students from the previous year, who did not have the clinical reasoning curriculum, formed the comparison cohort. Several modalities were used to teach clinical reasoning including whole case approach, serial cue approach, self-explanation of pathophysiological mechanisms and comparison of closely related diagnoses. The students interviewed a standardized patient and documented the history along with three likely diagnoses.

Results Students in the study cohort achieved higher scores on differential diagnosis (1.98 vs. 1.64 in the comparison cohort, p < 0.001). There was no statistically significant difference in the frequency of relevant symptoms queried between the study and comparison cohorts (3.74 vs. 3.34, p > 0.05).

Discussion Our study confirms that the introduction of clinical reasoning in a pre-clerkship clinical skills curriculum increases students’ ability to select relevant symptoms and provides them with a roadmap for expanding their differential diagnoses.