Background: In intensive care units (ICUs), nosocomial pneumonia is by far the most frequent nosocomial disease seen. Severe infections, complications, prolonged hospital admissions, and higher mortality rates are all brought on by the rise in antibiotic resistance. Objective: To identify the microbial causes of hospital-acquired pneumonia (HAP) and their antibiotic resistance pattern among ICU patients in Internal Medicine Department of Zagazig University Hospitals. Subjects and methods: In a cross-sectional study the sample size assigned was 72 patients. All of those who were adults had signs and symptoms of pneumonia started at least 48 hours after admission to the ICU and that occurs more than 48 to 72 hours after tracheal intubation. Results: The Most frequent organisms isolated were K. pneumonia, Acinetobacter baumannii complex and E. coli (42.9%, 18.6% and 14.3%, respectively). The most frequent sensitive drugs were colistin (48.6%) followed by imipenem, amikacin (both 18.6%). Most frequent intermediate drug was gentamycin (5.7%). Finally, most frequent resistant drugs were cefepime, ciprofloxacin and piperacillin (65.7%, 62.9% and 57.1%, respectively). There was a highly statistically significant increase in APACHE II score and mortality among dead compared to survived cases. Conclusion: HAP and ventilator-associated pneumonia (VAP) ICUs patients were mostly affected by K. pneumonia, Acinetobacter baumannii complex and E. coli, K. pneumonia was the most frequent organism. Most of the cases were resistant to cefepime, ciprofloxacin and piperacillin, most probably due to its cheap cost and easy availability.