Within the medial temporal lobe, significant attention has been paid to the analysis of the hippocampus (HC) in MR images because of its intimate connection to memory, emotion and learning. Volume changes in the HC have been recorded in conjunction with Alzheimer’s disease, post-traumatic stress disorder and depression. Recent studies have also found a significant reduction in HC volume that is related to gender; it is found in men but not women. In this paper we demonstrate a shape analysis of the HC and employ it to investigate gender di.erences in normal subjects. For each subject we extract the dominant medial sheet of the HC, find the plane defined by its two principal eigen vectors and then express the medial surface radius as a height function over this plane. This allows us to statistically quantify the relationship between several independent variables and local object width.