Background: Escherichia coliis a bacterial that caused infection. Amoxicillin is antibiotic ß-lactam that works by inhibiting the synthesis of the cell wall of bacteria and used to treat infectious diseases. Lysozyme is an enzyme that can kill certain bacteria, this enzyme works by lysing the bacterial cell wall.Escherichia coliresistens forEritomicin (100%), Amoxicillin (100%), Ampicillin (100%), Enrofloksasin (80%), and Oksitetrasicllin (20%). Objective: The objective of the research is to determine the effect of lysozyme in decrease the minimal inhibitory concentration Amoxcillin againstEscherichia coli. Methods: This study was experimental laboratory. The research is using bacteria Escherichia coli strain of local, Amoxcillin and lysozyme (sigma). Determining of inhibitory concentration of Amoxcillin, lysozyme and combination lysozymeAmoxicillin against Escherichia coli used dilution method. Result: The minimal inhibitory concentration Amoxicillin getEscherichia coli 166 µg/ml, lysozyme more than 300µg/mland combination Amoxicillin with lysozyme 12,3µg/ml.The results of analysis with the One Way Anova test obtained p>0,05. It’s indicates that the decline minimal inhibitory concentration Amoxicillin after added with lysozyme significant. Conclusion: Lysozyme does not have minimum inhibitory concentration effect againstEscherichia coli at concentration more than 300µg/ml. Combination lysozyme-Amoxicillin afford decrease minimal inhibitory concentration Amoxicillin against Escherichia coli.