Identification and representation of entities and their relationships relevant to an application are some of the key problems in logical data base design. This paper presents an approach to synthesizing logical segments that are representations of such entities and relationships. The major steps in this design are 1) collect all the pertinent functional relations in the application domain; 2) remove redundant relations to obtain a minimal covering set; 3 ) minimize the number of relations in the covering set to obtain an optimal set of relations in the third normal form; and 4) combine relations into logical segments according to prescribed performance requirements and projected information maintenance activities. Synthesis of logical segments for an airline reservations application is used as an illustrative example.