Two hundred and eighty-seven children with a total of 545 traumatized primary upper incisors were followed using standardized procedures until the age of 10. Extraction was the only treatment offered when intervention was necessary. The immediate as well as the long-term consequences of trauma were studied on the basis of this material. Consequences in the primary dentition comprised: color changes (53%), pulp necrosis (25%), pulp canal obliteration (36%), gingival retraction (6%), permanent displacement after luxation (5-22%), pathological root resorption (1-10%) as well as disturbances in physiological root resorption (4%) and, lastly, premature tooth loss (46%). In a multivariate analysis of the development of pulp necross in primary teeth after trauma, the following decisive factors were found: age of the patient at the time of injury, degree of displacement of the tooth as well as the degree of loosening and presence of crown fracture. The factors found to influence development of pulp canal obliteration were: displacement of the tooth at time of injury as well as detectable physiologic root resorption at time of trauma. The presence of crown fracture seemed to decrease the risk of obliteration. The need for scientifically based treatment strategies for managing and reducting complications after trauma in the primary dentition is stressed.