Comprehension of complex controlled vocabularies is often difficult. We present a method, facilitated by an object-oriented database, for depicting such a vocabulary (the Medical Entities Dictionary (MED) from the Columbia-Presbyterian Medical Center) in a schematic way which uses a sparse inheritance network of area classes. The resulting Object Oriented Health Vocabulary repository (OOHVR) allows visualization of the 43,000 MED concepts as 90 area classes. This view has provided valuable information to those responsible with maintaining the MED. As a result, the MED organization has been improved and some previously-unrecognized errors and inconsistencies have been removed. We believe that this schematic approach allows improved comprehension of the gestalt of large controlled medical vocabulary.