The aim of this study was to analyze the influence of toothpastes with or without green tea extract on the enamel hardness. Human teeth were used as specimens and surface enamel demineralization by soaking in 1% citric acid. Teeth that have been demineralized were applied with a toothpaste containing green tea extract with concentrations of up to 15% on the surface of the enamel teeth and then proceed with surface hardness measurement using Knoop system. The results showed that soaking the teeth (enamel) in a demineralized solution has significantly decreased the hardness of tooth enamel. Applications of toothpaste without (0%) and with green tea extract 5% or 10% or 15% on the demineralized enamel surface have increased the enamel hardness significantly. However, no significant differences were seen between the demineralized enamel and enamel applied with toothpaste containing green tea 5% or 10% or 15%. It was concluded that the application of toothpaste containing 5% green tea extract was able to increase the hardness of demineralized enamel.