Objective: To identify if a lecture or access to a computer aided learning (CAL) programme is more effective in teaching undergraduate dental students IOTN. Design: Prospective controlled trial. Setting: University Dental Hospital of Manchester, 1999 Subjects: Eighty-five 3rd year undergraduate dental students allocated by pseudo-randomisation to two groups. The first group received a lecture and seminar on IOTN, and the second group were given a seminar and access to a purpose written CAL programme. Main Outcome Measure: A standard test was given to the two groups in the form of ten sets of patient records that they had to score with IOTN Dental Health Component (DHC) and Aesthetic Component (AC). Results: There was no difference in mean score for the two groups with AC score (5·02 and 5·03). The CAL group of students performed best for DHC grade (mean score 5·41 compared with 4·24 for lecture group) and this was statistically significant (p <0.01). Conclusion: Undergraduate dental students can learn to use IOTN as well or better when using a CAL programme compared with a lecture.