Background & Aims: The present study compared fluoride uptake into enamel from sodium fluoride 0.05% gel and American Dental Association approved fluoride gel (Stannous fluoride 0.4% , Sultan Co.) when used on healthy enamel of the intact teeth. Methods: In an experimental study, 30 intact teeth extracted for orthodontic purposes were randomly assigned into two groups of 15 teeth. The teeth were sectioned in two mesial and distal halves as control and experimental sides. Defined semi-circular areas on the enamel of experimental halves were treated with gel for 4 minutes, the halves were stored in artificial saliva for 24 hours at 37 ºC, etched for 30 seconds by 0.5 M perchlorid Acid and washed by 0.2 ml KOH after each etching. Biopsy of the samples was obtained by Acid Etch Enamel Biopsy technique and the fluoride and calcium concentration were calculated by potentiometer and spectrophotometer respectively. Paired t test and student t test were used for statistical analyses. Results: The results showed significant increase of enamel fluoride content in the experimental halves after exposure to both stannous fluoride 0.4% (P=0.0001) and sodium fluoride 0.05% (P=0.009). Mean fluoride uptakes in stannous fluoride 0.4% gel and sodium fluoride 0.05% gel groups were respectively 4052.5 ppm and 892.5 ppm that shows statistically significant difference (P=0.0001). Conclusion: Although both sodium fluoride 0.05% and stannous fluoride 0.4% increased fluoride Content of tooth enamel after application, stannous fluoride 0.4% caused more fluoride uptake into the tooth enamel that is due to its higher amount of fluoride ion (1000 ppm) compared to sodium fluoride gel (225 ppm).