A total of 76 extracts from 35 plants available in the Turkish flora were assayed for their in vitro antibacterial activities against five pathogenic bacteria and a yeast. Sixteen crude extracts from eight plant species were found to possess an activity against at least one or more test microorganisms. Bioassay-guided fractionation of the most active crude extracts was also carried out with the most active extracts. Activity against Staphylococcus aureus, Bacillus cereus, Branhamella catarrhalis, Escherichia coli, Clostridium perfringens and Candida albicans (yeast) is discussed. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.