Background and purpose: The medlar (Mespilus germanica L., Rosaceae) is an edible fruit and modern medicine has recognized its healing properties in treatment of some diseases. There is no scientific data in literature about its activity against some bacteria. In this study, antibacterial activity of hydro-acetonic extract of medlar¢s leaf was evaluated against some bacteria.

Materials and methods: In this experimental study, the leaves were collected from Sari, Iran. Materials were dried at room temperature and coarsely ground before extraction. The extraction was performed at room temperature by maceration method using acetone (70%) as solvent. Total phenols and tannins were determined by Folin-ciocalteu method and antibacterial effects were studied. Minimal Inhibitory Concentration (MIC) and Minimal Bactricidal Concentration (MBC) were calculated by Broth Dilution Test.

Results: The yield of extraction was 20%. Total phenolic and tannins contents were 90±10 GAE (based on standard curve) and 10±4 /g extract, respectively. The extract showed best inhibitory and bactericidal activities against Klebsiella pneumoniae (MIC= 3.333 ± 0.0233 and MBC= 5.833 ± 0.065). The lowest MIC was observed against Vibrio Cholera (6.667±0.048) and the lowest MBC was seen against E. coli and Shigella dysentiea (9.167±0.042).

Conclusion: M. germanica leaf extract showed good antibacterial activities. So, this plant is potentially effective in controlling dysentery.