It has been known for a long time that many traffic accidents are not known to the police, but are dealt with by the health service. Because of this, the official statistics concerning persons injured in traffic, which are based on accidents known to the police, are misleading. In this study, data from the hospital records of the Swedish Board of Health and Welfare concerning treatment events terminated during the period 1998-2005 were therefore examined. On average, more than 12,100 people were annually treated in hospital because of road traffic accidents over the period 1998-2005. The level is slightly higher in the years after the turn of the century.