Some 14 ethanol extracts from 13 plant species collected from various regions of Turkey were assayed for in vitro antibacterial activity against two Gram positive and 5 Gram negative bacteria, using the disc-diffusion and dilution methods. The diameter of the inhibition zone in the disc-diffusion method shows that 12 extracts from the 14 plants studied have antibacterial activity in different levels. The broadest spectrum of activity was exhibited by Malva sylvestris against five bacteria, whereas the Verbascum spp. extract only showed activity against one. The highest antibacterial activity was produced by the extract of Hypericum perforatum. The minimum inhibitory concentration (MIC) values of plant extracts with antibacterial activity ranged from 0.125 to 4 mg/ml. The high MIC values showed that the extracts had low to moderate activity compared with standard antibiotics. Based on the results from the present investigation, it is concluded that most of the plants studied may be sources of antibacterial agents.