INTRODUCTION: Renewal of driver's licence because of illness or impairment involves a considerable number of doctors and inflicts burdens on many patients. The aims of this investigation were to describe the distribution of restricted driver's licences in diagnostic groups, the consequences of the renewal process and the reproducibility of the decision-making involved. MATERIAL AND METHODS: During a six-month period all driver's licences restricted due to illness or impairment from the Central Region of Denmark (population 1.2 million) were reviewed. Background information, sources of required information and recommendations were registered. The reproducibility was determined in 35 cases. RESULTS: A total of 923 cases were examined. The most frequent groups were insulin-treated diabetes (23%), epilepsy (20%), multiple sclerosis/ ALS/ Parkinson's disease (8%), and lipothymia (7%). In 78% of the cases, no further information than the standard form was needed. Further information was required from the general practitioner in 7% and from other specialists in 6%. In 6% of the cases, the assessment of the motor vehicle inspector was requested, and in 9% a driving test was required. The result was a non-restricted driver's licence in 9%, a time-restricted licence in 86%, a specially adapted vehicle in 8%, a temporary ban against driving in 3%, and 3% handed in their driver's licence. There were major differences between the diagnostic groups. The reproducibility of the recommendations was moderate (kappa = 0.35). CONCLUSION: The group of patients referred for renewal of driver's licence because of illness or impairment is heterogeneous and in most cases the result is a time-restricted driver's licence.