High-resolution genetic linkage maps are indispensable for positional cloning of disease genes. Current procedures for map construction, although aided considerably by many existing computer programs, require extensive user-intervention at each of many repetitive steps. This is time consuming, labour intensive and increases the chance of error. We have developed an expert system computer program, MultiMap, which automates this step-by-step procedure. MultiMap is based on a novel map construction algorithm and allows investigator control of marker locus characteristics, such as informativeness, scorability or distance to nearest neighbours. We used MultiMap to construct a human genetic map at an average resolution of 6 cM, using published genotypes at 1266 microsatellite markers, and further extended this map by adding 397 VNTR and polymorphic gene markers.