Longitudinal voxel-based morphometry studies have demonstrated increases in gray matter volume in hippocampal areas following extensive cognitive learning. Moreover, there is increasing evidence for the relevance of the subiculum in the context of learning and memory. Using longitudinal FreeSurfer analyses and hippocampus subfield segmentation the present study investigated the effects of 14 weeks of intensive learning on hippocampal and subicular gray matter volume in a sample of medical students compared to control subjects not engaged in any cognitive learning activities. We found that extensive learning resulted in a significant increase of right hippocampal volume. Volume of the left hippocampus and the subiculum remained unchanged. The current findings emphasize the role of the hippocampus in semantic learning and memory processes and provide further evidence for the neuroplastic ability of the hippocampus in the context of cognitive learning.