Aims: To explore the impact of a teaching resource on student’s understanding of variation in drug disposition between ethnic groups. Methods: A questionnaire was administered to students from medical and medical sciences undergraduate courses immediately before and after a teaching session on inter-individual variation in pharmacokinetics. Responses were analysed using a Wilcoxon signed rank test. Results: Students were most likely to define ethnicity in relation to culture, traditions, and place in contrast to use of the term in the pharmacokinetics literature where it refers to large-scale continental racial groups, e.g., Black, white, Asian. There was a tendency for students to assume a genetic mechanism for ethnic differences and there was a change in this assumption after they participated in the teaching session. Conclusions: Confusion around the use of the term ethnicity may contribute towards lack of clarity in teaching and in student understanding. Teaching about a range of mechanisms that can underly inter-individual variation in pharmacokinetic processes reduces the tendency of students to ascribe genetic mechanisms to differences in drug metabolism, clarifies some of the ways in which individuals can vary.