INTRODUCTION: Biomimetic enamel reconstruction is a significant topic in material science and dentistry as a novel approach for the treatment of dental caries or erosion. Compared to other conventional treatments, biocompatible and biodegradable chitosan hydrogel, with its antimicrobial properties shows promise as a biomaterial for the prevention, restoration, and treatment of defective enamel. OBJECTIVES: The present study was designed to investigate the effect of chitosan on the remineralization of enamel. MATERIALS AND METHODS Sound human premolars extracted for orthodontic reasons and were sectioned into 1mm thick slices.30 slices were selected and randomly divided into 3 equal groups (10 slices per group) as follows: GroupI: Control group, the slices were etched with 37% phosphoric acid for 30 seconds. Group II: The slices were etched with 37% phosphoric acid for 30 seconds, coated with bonding agent and chitosan hydrogel. Then slices were incubated at 37ºC in artificial saliva solution for 5 days. Group III: The slices were etched with 37% phosphoric acid for 30 seconds, coated with bonding agent and chitosan hydrogel. Then slices were incubated at 37ºC in artificial saliva solution for 10 days. After remineralization, the enamel surfaces were ultrasonically cleaned for 2 minutes and analyzed with scanning electron microscope (SEM) in order to observe induced structural changes on the enamel surface then elemental analysis and Ca/P ratios were carried out using Energy Dispersive Analysis X-Ray (EDAX) spectrometer. The obtained data were statistically analyzed. RESULTS: Morphological changes on the enamel surface after application of chitosan observed by SEM revealed the regeneration of an enamel-like layer in both treated samples. There was a statistically significant difference between the Ca/P ratios of the treatment groups compared to that of the control group. CONCLUSIONS: The ultrastructural and elemental alterations noticed in this study substantiate the use of chitosan in cases of dental erosions