A study was set up to determine the trends in medical impairment and work disability ratings for persons affected by whiplash associated disorders (WAD) and other injuries secondary to road traffic collisions, and into the influence of age, gender, professional status, and final medical impairment rating on final work disability. A cross-sectional study was carried out of insurance files of 2,523 subjects in 1989 and 3,223 subjects in 1994 judged to have a permanent medical impairment of 10% or more and work disability due to road traffic injury. Files were obtained from the Swedish Road Traffic Injury Commission. The main outcome measures were the crude frequency and age-specific, standardized percentage of traffic injuries with a medical impairment of 10% or more for the years 1989 and 1994. Final work disability status was analysed with respect to age, gender, type of injury, degree of medical impairment, and professional status. The proportion of medical impairment due to WAD was found to have increased from 16% in 1989 to 28% in 1994, but the proportion of work disability was found to have remained the same. Age over 40 years, low professional status, and having a medical impairment judgement of 15% or more were independently associated with reduced or full work disability.