The research on activity test of anti bacterial effect gel of citronella leaf (Cymbopogon nardus L. Rendle) on Staphylococcus aureushad been conducted. This research aims to determine the offect of carbopol concentration variation, and the concentration of extract, and the combination of both against gel stability and antibacterial activity to Staphylococcus aureus. Lemongrass leaf extract (Cymbopogon nardus L. Rendle) was obtained by maceration with 96% ethanol. The research design used ANOVA data analysis of complete randomized design of factorial pattern with variation of extract concentration of 5%, 10%, 15%, 20% and carbopol as gel base with homogeneity concentration, pH test, viscosity test, and anti bacterial activity test. The results reveal that variation of extract concentration affect the stability and activity of anti bacterial gel of lemongrass leaf extract. Variations in carbopolic concentration affect antibacterial activity but do not affect stability. Combination of vatiation of carbopoly concentration and extract affect anti bacterial activity. A good treatment combination wa obtained on formula A 1 B 4 , because it had the highest anti-bacterial activity of 14,56 mm.