In the present study the prevalence of white spot lesions (initial enamel lesions) on the vestibular surfaces was recorded in 19-year-olds subjected to and not subjected to orthodontic treatment. Fifty-one orthodontic patients and 47 untreated subjects were examined. On the average, 5.7 years had elapsed since orthodontic appliances were removed. The median white spot score was significantly higher in the orthodontic group than in the untreated group. The orthodontically treated subjects also had more teeth with white spot lesions than the untreated subjects. The highest prevalence was noted on the first molars in both groups. In the orthodontic group the mandibular canines and premolars and the maxillary lateral incisors were also affected. The present study showed that white spot lesions after orthodontic treatment with fixed appliances may present an esthetic problem, even more than 5 years after treatment.