CARDIAC injury, secondary to nonpenetrating trauma, is becoming an increasingly important entity in this age of high speed transportation, industrial mechanization and community social violence. One of the subtle, uncommon, but frequently hemodynamically significant, lesions produced is traumatic tricuspid insufficiency. During the past several years we have managed five patients in whom this diagnosis was established. Because of the rarity of this lesion, the variations in its clinical course and our belief that its occurrence is more common than thus far suspected, we are presenting several representative cases in detail combined with a review of all known patients including those found in the literature. Report of Cases Case 1. —A 28-year-old navigator was admitted to the National Defence Medical Center in Ottawa, on Aug 10, 1962, having been involved in a car accident in which he sustained a closed head injury, lacerations of his face and multiple rib fractures with