The purpose of this report is to demonstrate that the ability to produce keratoconjunctivitis (KC) is a property found in Salmonella weltevreden. This observation is contrary to previous reports that Salmonella spp. do not produce KC. An outbreak of KC due to S. weltevreden occurred in a guinea pig colony, and the animals carried the organism in the intestinal tract. The same Salmonella serotype that caused an epidemic of diarrhea in humans and a routine laboratory isolate also possessed the ability to induce KC. Unlike Shigella spp. (the prototype organisms positive for KC), S. weltevreden induced KC and bound Congo red dye even when grown at 30 degrees C. It invaded HeLa cells in culture but did not hybridize with a DNA probe for invasiveness of Shigella spp. and enteroinvasive Escherichia coli even though it harbored plasmids. It was susceptible to all the antibiotics tested, was hydrophobic, and showed mannose-sensitive hemagglutination. It did not have enterotoxic or cytotoxic activities.