The incidence of rib fractures secondary to trauma has not been clearly reported. Of the 7147 patients seen by our trauma service from January 1987 to June 1992, 711 (10%) had rib fractures. Among the patients with rib fractures, 84 (12%) died, 670 (94%) had associated injuries, 274 (32%) had a hemothorax or pneumothorax, and 187 (26%) had a lung contusion. Fifty-five percent of the patients required an immediate operation or admission to the intensive care unit. Thirty-five percent of the patients required discharge to an extended care facility and 35% developed a pulmonary complication. We conclude that rib fractures are a marker of severe injury in which (1) 12% will die because of their injuries, (2) more than 90% will have associated injuries, (3) one half will require operative and ICU care, (4) one third will develop pulmonary complications, and (5) one third will require discharge to an extended care facility.