Mardiana RN, Handayani N. 2016. Antibacterial activity of the sambiloto leaf extracts (Andrographis paniculata) to Bacillus cereus and Pseudomonas aeruginosa. Biofarmasi 14: 19-24. The purpose of this research was to evaluate the antibacterial activity of sambiloto ( Andrographis paniculata Nees. ) extract against bacterial Bacillus cereus and Pseudomonas aeruginosa. Some research had proven sambiloto leaf extract evident had antibacterial activity to bacteria Staphylococcus aureus. The sample of sambiloto leaf was macerated using 70% ethanol, and the extract was concentrated using rotary evaporator. The antibacterial activity was evaluated by diffusion method. Antibacterial potency of the extract was compared with by Amoxicillin made default curve among logarithm concentrates to constraining diameter (mm), then accounted by its equivalence point. Ethanol extract of sambiloto leaf had antibacterial activity to B. cereus and P. aeruginosa. Minimum Inhibitory Concentration (MIC) of 12,5% against B. cereus and P. aeruginosa. The potential antibacterial activity of sambiloto leaf extract was 0,2% for B. cereus and 0.3% for P. aeruginosa; as compared with Amoxicillin. This, potential antibacterial activity of sambiloto leaf extract to the two tested bacteria was much smaller than that of Amoxicillin synthetic antibiotic.