Back ground: Colistin is considered the last option for severe infections caused by multidrug resistant Gram negative bacteria. The emergence of its resistance constitutes a very serious problem; hence, this study was established. Objectives: This study aims to estimate prevalence of colistin resistance among the clinical isolates of E.coli and k.pneumoniae with detection of the presence of mobilized colistin genes mcr-1 and mcr-2 in those resistant isolates as a possible molecular mechanism for such resistance. Methodology: This cross-sectional study was performed in the Medical Microbiology and Immunology Department, Faculty of Medicine, Zagazig University between January and August 2019. Two hundred isolates of our target organisms were obtained out of 324 specimens from patients admitted at Zagazig University Hospitals. A minimum inhibitory concentration (MIC) of colistin was detected by broth microdilution method. Isolates were reported as resistant if MIC ≥4μg/mL according to CLSI guidelines. PCR for mcr-1 and mcr-2 was done for all colistin resistant isolates. Results: Twenty four (24) isolates resistant to colistin were obtained out of 200 E.coli and k.pneumoniae isolates. Among 24 colistin resistant isolates, we detected mcr-1 gene by PCR in only 2 isolates (8.4%); one E.coli (4.2%) and the other is K.pneumoniae (4.2%) strain. Mcr-2 wasn't detected at all. Conclusion: This study detected the presence of colistin resistance among k.pneumoniae and E.coli isolates from Zagazig University Hospitals by mcr-1 gene but not by mcr-2.