Lime leaves (Citrus hystrix) contains alkaloids, flavonoids, tannins, and essensial oils that can inhibit the growth Streptococcus mutans which bacteria that be cause of caries dentis. The study was conducted to know the formulation of extract of lime leaves (Citrus hystrix) and to know the effectiveness of toothpaste extract of lime leaves (Citrus hystrix) against Streptococcus mutans. Toothpaste extract of lime leaves (Citrus hystrix) was made refers to the draft formula by Sari (2014), it tested of quality use homogenity test, organoleptic test, and pH test. Toothpaste extract of lime leaves (Citrus hystrix) 5%, 15%, 25%, without the extract and control positive (Pepsodent®) in test using diffusion method using TSA. The antibacterial power calculation using measurements of the zone of inhibition. The data of quality evaluation of toothpaste was analyzing with descriptive. The data were analyzed using One-way ANOVA test and continued with the Tukey test. The average diameter of the inhibitory zones toothpaste extract of lime leaves concentrations of 5%, 15%, 25%, without extract and control positive (Pepsodent®) in row are 2,06; 2,96; 3,83; 0 and 12,50 mm. Toothpast extract of lime leaves concentrations of 25% is better based quality evaluation test.Toothpast extract of lime leaves (Citrus hystrix) with concentrations of 5%, 15% and 25% can inhibit the growth of Streptococcus mutans bacteria but it not as effective when compare of the control positive (Pepsodent®).