Many important issues in the design and implementation of hypermedia system functionality focus on the way interobject connections are represented, manipulated, and stored. A prototypic system called HB1 is being designed to meet the storage needs of next-generation hypermedia system architectures. HB1 is referred to as a hyperbase management system (HBMS) because it supports, not only the storage and manipulation of information, but the storage and manipulation of the connectivity data that link information together to form hypermedia. Among HB1's distinctions is its use of a semantic network database system to manage physical storage. Here, basic semantic modeling concepts as they apply to hypermedia systems are reviewed, and experiences using a semantic database system in HB1 are discussed. Semantic data models attempt to provide more powerful mechanisms for structuring objects than are provided by traditional approaches. In HB1, it was necessary to abstract interobject connectivity, behaviors, and information for hypermedia. Building on top of a semantic database system facilitated such a separation and made the structural aspects of hypermedia conveniently accessible to manipulation. This becomes particularly important in the implementation of structure-related operations such as structural queries. Our experience suggests that an integrated semantic object-oriented database paradigm appears to be superior to purely relational, semantic, or object-oriented methodologies for representing the structurally complex interrelationships that arise in hypermedia.