N eem leaf (Azadirachta indica Juss) is a plant that grows wild in the woods or a somewhat barren area. Neem leaf contains several phytochemical compounds efficacious as an antibacterial and antifungal such as alkaloids, saponins, tannins, phenolic, flavonoids, triterpenoids and is believed to cure some diseases. Bacteria that is often present on the tooth after tooth extraction is a bacteria Streptococcus mutans. Dry socket is defined as the alveoli not occupied by a blood clot and is the most common complications after tooth extraction done. The purpose of this study is to know the antibacterial effect of extracts of neem leaf against the bacteria Streptococcus mutans. Neem leaf extract obtained by maceration using ethanol solvent. At the bacterial activity test performed by agar diffusion. This study is divided into two stages: namely extraction and bioassay. In the bioassay it was conducted two tests, namely a preliminary test and test of treatments. Negative and positive control using chlorhexidine, tetracycline and distilled water. The incubation period of 24 and 48 hours at a temperature of 370C. Inhibition zone formed was calculated using a caliper. The results of this study were tested and analyzed using SPSS 22.0 of statistical method of normality test, homogeneity, one-way ANOVA and Post hoc LSD. The results of the analysis of bacterial inhibition zone diameters at concentrations of 10%, 20%, 30%, 40%,50% respectively are 27.5 mm, 28.2 mm, 29.15 mm, 29.55 mm, 30.15 mm, Chlorhexidine 23.5 mm, Tetracycline 22.3 mm, Distilled O mm on a 24-hour incubation period and 28.3 mm, 28.5 mm, 29.85 mm, 30.05 mm, 30.55 mm, Chlorhexidine 23 8 mm, Tetracycline 22.5 mm, Distilled O mm on a 48-hour incubation period. Based on this study, extracts of neem leaves (Azadirachta indica a Juss) has an antibacterial effect against bacteria Streptococcus mutans.