Mother in law’s tongue plant has some active compounds inter alia saponin, polyphenol, and flavonoid that have antibacterial effects. This study aimed to identify whether the antibacterial effects of mother in law’s tongue leaf (Sansevieria Trifasciata) towards the growth of Escherichia coli and Streptococcus sp. This was an experimental laboratory study. The concentrations of mother in law’s tongue leaf extract were tested with well methods, as follows: 5%, 10%, 20%, and 40%. The results showed that this extract at concentration of 5%, 10%, 20%, and 40% could inhibit the growth of E. coli with the average diameters of inhibition zones as follows: 7.8 mm, 13 mm, 14.5 mm, and 17.3 mm meanwhile of Streptococcus sp. with the average diameters of inhibition zones, as follows: 4.6 mm, 9.6 mm, 13 mm, and 15.3 mm. Conclusion: Ethanol extract of mother in law’s tongue leaves (Sansevieria Trifasciata) has antibacterial activities against the growth of E. coli and Streptococcus sp. The higher the concentration is, the broader the inhibition zone is.Keywords: Sansevieriae trifasciata folium, inhibition zone, E. coli, Streptococcus sp. Abstrak: Tanaman Lidah Mertua (Sansevieria Trifasciata) memiliki senyawa aktif yaitu Saponin, Polifenol, dan Flavonoid yang mampu bekerja sebagai antibakteri. Penelitian ini bertujuan untuk mengetahui ada tidaknya daya hambat ekstrak daun lidah mertua (Sansevieria trifasciata) terhadap pertumbuhan bakteri E. coli, dan Streptococcus sp. Jenis penelitian ini eksperimental laboratorik. Kadar ekstrak etanol daun lidah mertua (Sansevieria trifasciata) yang diujikan dengan metode sumuran yaitu 5%, 10%, 20%, dan 40%. Ekstrak etanol daun lidah mertua (Sansevieria trifasciata) dengan konsentrasi 5%, 10%, 20%, dan 40% dapat menghambat pertumbuhan bakteri E. coli dengan rerata diameter zona hambat masing-masing yaitu 7,8 mm, 13 mm, 14,5 mm, dan 17,3 mm sedangkan Streptococcus sp. dengan masing-masing rerata diameter zona hambat yaitu 4,6 mm, 9,6 mm, 13 mm, dan 15,3 mm. Simpulan: Ekstrak etanol daun lidah mertua (Sansevieria trifasciata) mempunyai aktifitas antimikroba terhadap pertumbuhan bakteri E. coli dan Streptococcus sp, dimana makin tinggi konsentrasi ekstrak daun lidah mertua, makin luas zona jernih pada media kultur bakteri E. coli dan Streptococcus sp. Kata kunci: Sansevieriae trifasciata folium, daya hambat, E. coli, Streptococcus sp.