This study analyzed traumatic injuries in the primary and permanent dentition in children treated from 1990 to 1992 at the Children's Dental Traumatology Service in Valparaiso, Chile. A total of 227 records from patients 2 to 21 years old was studied with regard to the cause of injury, location of injury, time elapsed before treatment, history of previous trauma, type of injury, number of injured teeth, and how patients seek treatment. A total of 73 patients had injuries to the primary dentition (pD) and 154 to the permanent dentition (PD) with a total of 357 injured teeth (115 primary, 242 permanent). Ten to 12-year-old children had the highest number of injuries (33%). Falling was the most common cause of injury in both groups (82% pD, 58% PD), followed by striking against objects (13% pD, 19% PD) and bicycle accidents (9% PD). Most injuries in children with primary dentition (68%) occurred at home, while children with permanent dentition had most accidents at school (38%). Most children (61%) sought treatment after 24 h (52% pD, 65% PD), 61 children had suffered previous trauma (36% pD, 23% PD). The most common injuries in primary teeth were luxation (26%), intrusion (21%) and subluxation (18%). Uncomplicated crown fracture (34%), followed by complicated crown fracture (21%), were the main injuries in permanent teeth. There was no difference in the number of teeth involved for either dentition. A single tooth injury was found in 54%. Two teeth were involved in 35%, and three or more teeth in 11%.(ABSTRACT TRUNCATED AT 250 WORDS)