Abstract Objective. To investigate the effect of daily intake of fluoridated milk on enamel demineralization adjacent to fixed orthodontic brackets assessed with quantitative light-induced fluorescence (QLF). Materials and methods. Sixty-four healthy adolescents (13-18 years) undergoing orthodontic treatment with fixed appliances were enrolled and randomly allocated to a randomized controlled trial with two parallel groups. The intervention group was instructed to drink one glass of milk (~ 200 ml) supplemented with fluoride (5 ppm) once daily and the subjects of the control group to drink the same amount of milk without fluoride. The intervention period was 12 weeks and the end-point was mineral gain or loss in enamel, assessed by QLF on two selected sites from each individual. The attrition rate was 12.5% and 112 sites were included in the final evaluation. Results. There was no statistically significant difference between the groups concerning fluorescence (¿F) values and lesion area (A mm(2)) at baseline. After 12 weeks, a significant decrease (p <0.05) in ¿F was registered in the fluoridated milk group and a significant increase in the non-fluoride control group (p <0.05). The mean reduction in the test group was somewhat lower (14%) than the increase in the control group (18%), but individual variations were evident. Only minor alterations of lesion area were recorded over the 12-week period and no statistically significant differences compared with baseline were found in any of the groups. Conclusion. Daily intake of fluoridated milk may aid remineralization of white spot lesions adjacent to fixed orthodontic appliances.