A method is described that uses the ABI PRISM 310 genetic analyzer in conjunction with custom-designed software to identify and classify RAPD products. This methodology will also work well with AFLPs and microsatellite analyses. The methodology uses the ABI PRISM 310's high-throughput (> 500 samples per week) capabilities and in-lane molecular weight standards to efficiently separate and size DNA products. Peak detection, locus classification and export of the data in a form accessible by several genetic analysis programs were accomplished through a custom-written software program (Peaks). Various criteria used by the program to identify and classify loci are described, and their effect on population analyses is examined. Criteria providing an effective, robust determination of population structure are presented.