Between August 1986 and July 1987 more than 24,000 households, containing nearly 67,000 persons, were surveyed by telephone about traffic injuries during the past three months. Expressed on an annual basis, approximately 430,000 people, or about 1 in 34 of the Dutch population, had suffered some sort of injury in a road accident. The road traffic morbidity was, therefore, 2,942 per 100,000 inhabitants. Of these, about 135,000 had to be treated in hospital (20,000 as inpatients). More than 100,000 did not need treatment. Cyclists formed by far the largest category of road user, but mopedists had the highest injury rate per kilometer travelled. 210,000 of these casualties fell within the definition for recording by the police. The police recorded only 49,748 traffic casualties, or about 25%, during the same period. The police data were not representative; the completeness declined according to severity of the injuries: inpatients, about 70%; outpatients 26%; extramural about 11%. Cyclists (11%), children (9%), and single vehicle accidents (5%) were very much underrepresented. The largest category of road user is cyclists, not car occupants as indicated by the police data. A number of recommendations are made for supplementing the police data and the existing hospital inpatient data. These include extending the Home Accident Recording System of outpatients and the General Practitioner Panel to include road accident victims. Together a representative sample of 95% of all those receiving medical treatment would thus be obtained.