Antimicrobial activity of methanol piper nigrum extract in combination with some antibiotics was investigated against Escherichia coli isolated from chicken samples. The in-vitro antimicrobial sensitivity pattern of these isolates was done and the intermediate isolates were checked for combination with methanol piper nigrum extract after detecting their antimicrobial activities against these isolates by both disc diffusion test and MIC and the obtained data showed that antimicrobial activities of amoxicillin, doxycycline ,gentamicin, erythromycin and cefotaxime were enhanced in combination with methanol piper nigrum extract. The obtained data showed that enhancement by both disc diffusion test and MIC for methanol piper nigrum extract and each of the mentioned antibiotics in decimal assay of additivity ratio was (0.5 for amoxicillin, cefotaxime and 0.5 for extract and 0.4 for doxycycline ,gentamicin, and erythromycin and 0.6 for extract) against E.coli isolates.