Magnetic resonance imaging (MRI) has made possible non-invasive research on the living human brain. However, three-dimensional display of areas obscured by the operculum deep within the cortex has been difficult. This study used MRI in an attempt to establish a three-dimensional method of displaying an obscured brain structure (the insula). A three-dimensional image of the insular cortex was constructed from horizontal MR images. As a result, the major anatomical landmarks of the insula were clearly displayed. This method makes possible non-invasive display and analysis of obscured structures deep in the brain, overcoming the disadvantage presented by the use of sectional images.