Dog bites are a medical problem for millions of people, children being the most common victims. Human deaths attributable to dog bite injury (not rabies) are relatively infrequent. There have been some epidemiologic reviews, but this study is the first attempt to arrive at an understanding of bites involving predation on human beings by conducting behavioral examinations under controlled conditions of the dogs involved, and by interviewing victims, witnesses, and people familiar with the animals.The three cases studied involved two fatalities and an attack that was nearly fatal. The victims were 11, 14, and 81. In each case, owned pet dogs consumed some human tissue. The severity of the victims' injuries was not the consequence of a single dog bite, but the result of repeated attacks by dogs behaving as a social group. Factors that might contribute to a dog's regarding human beings as potential prey were examined, including hunger, prior predation, group behaviors, defense of territory, previous interactions with people, the presence of estrous female dogs, and environmental stimuli. In two of the cases, it was possible, by using similar stimuli, to duplicate the circumstances at the time of the attack.The results of the observations showed the value of behavioral analysis and simulations methods in evaluating possible factors in dog attacks.Among the many factors probably involved in severe dog attacks are the size, number, and nutritional status of the dogs; the dogs' previous aggressive contacts with people; the victim's age, size, health, and behavior; and the absence of other human beings in the vicinity.