A single-blind, randomized controlled trial was conducted in 207 children (12 years-old) living in a non-fluoridated area to ev~luate the efficiency of Shellac F in dental caries prevention. Shellac F and Duraphat were applied in two experimental groups every 3 months, and no application of fluoride varnishes was done in the control group. Dental caries were evaluated according to the International Caries Detection and Assessment System (ICDAS II) by 3 calibrated examiners. After 12 months, the mean scores of new carious teeth and teeth surfaces of the two experimental groups were significantly lower than that of the control group (p 0.05) in S1 code. There was no significant difference observed between the two experimental groups (p 0.05). However, the percentage of dental caries reduction was 29 percent in Shellac F and 11 percent in Duraphat treated groups compared to the control groups (p 0.05). This study demonstrated that Shellac F and Duraphat were both effective in dental caries prevention in 12 years-old children after 12 months.