We used automated ribotyping on the RiboPrinter Microbial Characterization System to study the epidemiology of listeriosis in western Austria over the period 1988-1996. Thirty-six isolates containing three serotypes were included in this collection. Each of the 16 ribotype groupings (RiboGroups) produced in this study contained a single serotype. Isolates collected from within a single food factory environment all grouped into unique RiboGroups. One factory contained isolates showing two unique RiboGroups, both of which were also seen in patient isolates. This same set of Listeria isolates has previously been studied by automated laser fluorescence analysis of randomly amplified polymorphic DNA (RAPD-Alfa). The data produced by the RiboPrinter system correlated well with the epidemiological information, better than the results achieved with RAPD-Alfa. The RiboPrinter system provides a rapid, easy, and useful method for the typing of Listeria monocytogenes.