Background: Since the end of the 1960ies, accidents have been identified as the most common cause of mortality in children and account for considerable childhood morbidity in industrialized western countries. In contrast to traffic-related accidents in older children and adolescents, which were consequently registered and documented, no epidemiological data exist about home injuries and accidents during the first years of life in Germany. This report presents data on accident-related hospitalizations in a cohort of 10271 infants,who participated in a prospective vaccine efficacy trial in Germany from 1991 to 1994. Methods: From the time-point of study entry (at the age of 2-4 months) until the end of the study (December 15, 1994) study families were biweekly contacted by phone using a standardized questionnaire, asking for medically-relevant events and hospitalizations. Results: Overall 1598 hospitalizations in 1282 study children were reported. Accidents were responsible for 338 hospitalizations (21.2%) in 319 children (57.1% boys). Two children died (one after a traffic accident and another one after drowning); mortality was 0.6%. The peak accident incidence was at the age of 9-12 months with 22 events/1000 observation years. Most accidents occurred in May (10.9%) and September/October (11.8%). Thursday was the day on which most accidents occurred (n=61, 18.1%). 72.5% of all accidents (n=245) were caused by physical trauma of kinetic (n=227) or thermic nature (n=18). Only 12 accidents (3.5%) were traffic-related. Head trauma was the most frequent accident (n=193, 57.2%), followed by ingestions (n=79, 23.4%), injuries (n=20, 5.9%), extremity-fractures (n=19, 5.6%), scalds/burns (n=18, 5.3%) and aspirations (n=9, 2.6%). Overall 12.7% of all hospitalizations registered during the study period were accident-related. Mean duration of hospitalization ranged from 1.3+/-1.2/1.9+/-1.8 d (ingestions, injuries) to 9.8+/-8.3/11.4+/-11.8 d (burns/scalds/fractures of the extremities). Children without siblings, cared by one parent showed the lowest, children with more than two siblings in families with four or more adults showed the highest accident rate (1.6 vs. 4.4%). Conclusion: Accidents in infants and toddlers represent an important, although generally underestimated childhood morbidity factor with higher incidence rates but lower mortality compared to accidents in older children.