A Clostridium sp., associated with an unusual spoilage of vacuum-packaged refrigerated uncooked (fresh) and roasted beef, was isolated as a pure culture from the spores in spoiled beef. The pure culture was used to study important characteristics and to differentiate it from other clostridial species usually found in beef. The biochemical characteristics, volatile fatty acid and soluble-protein profiles, temperatures and pHs of growth, and temperatures of sporulation, germination, and destruction of the isolate were distinctly different from other Clostridium spp. studied. It is not toxigenic and has 26% guanine plus cytosine. The isolate is a new species and is named Clostridium laramie .