An investigation into mandibular retrusion and the relationship between the maximum intercuspal position and the most retruded mandibular position was conducted on 15 dental students and nurses who had reasonably intact dentitions and a well-defined intercuspation. A photographic method was used to measure the retrusion that occurred at the occlusal surfaces of the posterior teeth. An average of approximately 0.2 mm retrusion was found, and the explanation of the relatively large "apparent" retrusion led to a discussion of the mandibular axes of opening.