Whitening toothpaste are easily obtained over the counter by consumers. The aim of this study was to assess the side effects of whitening toothpaste on enamel roughness and micro hardness which might contribute to increase caries risk. Methods: Enamel specimens were obtained from 60 unidentified freshly extracted human premolars. The enamel specimens were randomly divided into three groups; whitening toothpaste containing perlite, whitening toothpaste containing -phtalimido peroxycaproid acid (EURECO Ⓡ HC, Indonesia), and non-whitening toothpaste as control. Tooth brushing was performed equal to 1 and 3 months. Surface roughness tester was used to determine enamel roughness and Knoop Micro hardness tester was used to determine enamel micro hardness. Results: There were statistically significant differences in enamel roughness after 1 and 3 months equivalent tooth brushing between three groups. There were significant differences in enamel micro hardness values for all groups after three months-brushing which showed a decrease in micro hardness for whitening groups and an increase in micro hardness for non-whitening group. Conclusion: Tooth brushing with whitening toothpaste for a prolonged time increases enamel roughness and decreases enamel micro hardness, which in turn increases the potential of caries risk.