Polar extracts of the leaves of Millingtonia hortensis showed good antimicrobial activity. Twenty different bacterial strains and two yeast cultures were used. The aqueous alcohol extract showed good activity against all microbes tested, particularly Escherichia coli and Salmonella typhimurium , both Gram-negative bacteria, with MIC values of 6.25 µg/ml. The activity is compared with known antibiotics such as gentamycin and nystatin.