The javelina, or collared peccary (Pecari tajacu), is indigenous to Arizona, New Mexico, and Texas in the United States and ranges throughout Latin America. From June 2004 to April 2005, an estimated 105 javelinas died in a mortality event that occurred in Tucson, Arizona, and neighboring areas. Clinical signs observed in sick animals included emaciation, dehydration, lethargy, and diarrhea. In addition, some animals showed labored breathing and hind limb weakness. We necropsied 34 animals, and enteritis was the most frequent clinical sign, followed by colitis, pulmonary congestion, and pneumonia. The only consistent findings were isolations of Clostridium perfringens type A and multiple Salmonella serotypes. Although it is likely that these javelinas ultimately succumbed to salmonellosis, it is unclear whether other unidentified underlying factors were involved. This is the first reported case of widespread salmonellosis in free-ranging javelinas.