The study aimed to determine the antibacterial activity of Kantutay (Lantana camara L.) crude leaf extract against Gram-positive and Gram-negative bacteria. Ethanolic leaf extract was prepared by rotavaporation and its antibacterial activity determined by the Kirby Bauer Method. Using Gentamicin (10μg) / Tetracycline (30μg) as positive control and distilled water as negative control, the extract was tested against reference strains of Gram-positive Bacillus cereus (ACTCC 11778) and Bacillus subtilis (ATCC 11774), and Gram-negative Pseudomonas aeruginosa (ATCC 25619) and Escherichia coli (ATCC 25922). The Zones of Inhibition (ZI) were measured in millimeters using a caliper. Results of the experimentation showed that the grand mean Zone of Inhibition (ZI) of Kantutay leaf extract against Gram positive bacteria B. cereus and B. subtilis were 11.9mm and 14.4mm, respectively; while a 0mm ZI was observed against Gram-negative P. aeruginosa and E. coli. Results further exhibit that Kantutay (Lantana camara L.) crude leaf extract was inactive in inhibiting P. aeruginosa and E. coli (gram negative bacteria) growth, partially active in inhibiting the B. cereus growth, and active against B. subtilis. Hence, it may be concluded that Kantutay crude leaf extract does not have antibacterial effect against Gram-negative bacteria like P. aeruginosa and E. coli but have antibacterial effect against Gram positive bacteria like B. cereus and B. subtilis.