Case histories were studied of 286 patients treated for mandibular fractures by the Department of Plastic Surgery in conjunction with the Dental Department at Odense University Hospital between 1964 and 1973. 46.5% of the patients were aged 18-30 years; and 73.4% were male. Mandibular fractures associated with mid-face fractures were most frequently caused by traffic accidents (81%). When the mandible alone was fractured traffic accidents accounted for 50%, while assaults were responsible for 20%. Accidents at work only occurred among the men. Of the 487 mandibular fractures the most frequent site was the condylar process (36%) where half of the fractures in women were localized. Assaults most frequently caused fracture of the angle of the mandible; while falls were most frequently responsible for fracture of the condylar process. The fracture distribution in dentulous and edentulous mandibles differed despite the aetiology being the same.