We studied causes of mandibular fractures treated in oral and maxillofacial units in three countries in years 1990-2000 in Kuwait (n=596), 1995-2000 in Canada (n=228), and 1990-99 in Finland (n=268). Of the Finnish patients, 27% were women. Corresponding percentages in Kuwait and Canada were 13 and 17%, respectively. Traffic crashes were the cause of injury in 55% of the cases in Kuwait and 33% in Oulu, but only 7% in Toronto. In Kuwait, the victims were often young people, which is why more traffic education, more control of speed, and more control of the use of safety belts should be implemented. Assault was the cause in 54% in Toronto, 12% in Kuwait, and 37% in Oulu. Falling was the cause in 22% of the cases in Kuwait. Alcohol was implicated in 21% of cases in Canada and 15% in Finland.