objectives : This study was performed to investigate the effects of Agrimonia pilosa Ledeb. extracts on growth inhibition of Escherichia coli KCTC 2441. methods : Measured growth inhibition of Escherichia coli KCTC 2441 by concentration of the Agrimonia pilosa Ledeb. extract and collection periods of the Agrimonia pilosa Ledeb. and picking region of the Agrimonia pilosa Ledeb. results : The Agrimonia pilosa Ledeb. estrct is effective on retarding growth of Escherichia coli KCTC 2441. At 5% the growth of Escherichia coli KCTC 2441 was suddenly retarded. The stem of Agrimonia pilosa Ledeb. extract in a sunny place on June is more effective then its leaf. conclusions : These results suggest that Agrimonia pilosa Ledeb. extract is effective in growth inhibition of Escherichia coli KCTC 2441.