We have developed a computer representation of metabolic pathways that incorporates metabolic reactive spaces, species distinctions, and reversibility considerations. Furthermore, the distinction is made between pathway substrates and cosubstrates. Reactions are represented as entries in a database; the code was developed under dBASE III+. Two views onto the database have been developed: a spanning tree which performs a depth search and a stepwise navigational approach which offers reaction possibilities one at a time. In addition, metabolic pathways of any desired starting point are output as a Warnier diagram.