The study of the antibacterial activity of flavonoid extracts of Ephedra alata was carried out on Gram positive and Gram negative pathogenic bacteria. The results exhibited variable susceptibilities of microorganisms for different concentrations of flavonoid extracts. The activity was associated with high concentration. Using plate methods, the extracts of Ephedra alata displayed relatively important effects with a variable diameter of growth inhibition zones in most types of bacteria. However no effect was recorded against Serratia marcescens ATCC 13880 with butanol extracts of flowers and leaves and ethyl acetate and dichloromethane extracts of leaves as well as with butanol, ethyl acetate, and dichloromethane extracts of leaves against Enterococcus faecalis ATCC 29212.
