Pasteurella multocida is a common cause of infection following bites or scratches caused by dogs and (especially) cats. It is rarely reported, however, and apparently often overlooked as a pathogen. The typical clinical manifestation is a rapidly developing cellulitis at the site of injury. The infection is potentially dangerous and can cause a chronic local infection of deep tissues and osteomyelitis. It responds well to several antimicrobials, with penicillin being drug of choice. Fifty-five patients are reported--72% with cat bites and/or scratches and 28% with dog bites. Ninety-two percent of the wounds went deeply through the skin. All patients presented for treatment 12 to 72 hours after receiving the animal wounds to their hands. Drainage from all wounds was serosanguineous or purulent, and cultures taken were positive for P. multocida. All of the wounds responded to surgical drainage and penicillin. One patient developed osteomyelitis. The acute onset of cellulitis, lymphangitis, and serosanguineous or purulent drainage from hand wounds 12 to 24 hours after cat or dog bites should suggest P. multocida as the predominant etiologic agent. Immediate surgical drainage and penicillin therapy is the treatment of choice.