The aim of this study was to investigate, describe and analyse how the problem of root resorption is handled in a large orthodontic clinic and if these approaches were in accordance with the recommendations and guidelines described in the literature, and to estimate the prevalence of root resorption found in the radiographic material. All records of patients who terminated active treatment with fixed or removable appliances during the year 2004 at the Department of Orthodontics, University Clinics of Odontology, Goteborg, Sweden were examined (902 patients). In 837 records adequate information was obtained. The factors studied included: the presence of journal recordings of predisposing factors, the presence of radiographic examinations before, during and after treatment, the frequency of radiographic examinations and the prevalence of moderate or severe root resorption reported. The most frequent registrations were for trauma, and nail biting. Before treatment 81.5% of the patients were examined with periapical radiographs. After 6 months of treatment the percentage was 54.5%, while 15.8% of the patients were examined twelve months after treatment. At the end of treatment 52.5% of the patients were examined. When moderate root resorption was diagnosed during treatment the use of lower forces, resting periods and decrease of the treatment duration were the most common preventive measures. The prevalence of light root resorption was 1.9%, 3.2%, 4.9% and 8.6% at the beginning, after 6 and 12 months and at the end of treatment, respectively. Severe root resorption was found in 1.9% at the end of treatment. In conclusion before treatment periapical radiographs were taken in most cases. The percentage of the radiographs dropped significantly at 6 and 12 months. At the end of treatment half of the patients were examined with periapical radiographs. When moderate root resorption was diagnosed the use of lower forces, resting periods and decrease of treatment time were common preventive measures. Light root resorption was found in less than 10% while severe root resorption was noted in 2% after active treatment.