Abstract: Objective To study the distribution of pathogenic bacteria in Affiliated Hospital of Liaoning Medical College from 2009 to 2011 and their sensitivity to antibiotics. Methods The distribution of 3 947 pathogenic bacteria isolated from different clinical samples in January 2009–December 2011 and their sensitivity were retrospectively analyzed. The isolated pathogenic bacteria were identified with Microscan walkaway-96 automatic identifier and their drug sensitivity was tested. Results Of the 3 947 isolated pathogenic bacteria, 3 169 (80.3%) were Gram-negative and 778 (19.7%) were Gram-positive. Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii were the frequently isolated Gram-negative bacteria. ESBLsproducing Escherichia coli and Klebsiella pneumoniae accounted for 55% and 45%, respectively. Staphylococcus aureus and Staphylococcus epidermidis were the main Gram-positive pathogens. No vancomycin-resistant Staphylococci were detected. The number of MRSA-resistant Staphylococci aureus increased significantly. Conclusion The distribution of pathogenic bacteria was significantly changed from 2009 to 2011 with their sensitivity to antibiotics decreased, indicating that antibiotics should be rationally used in clinical departments according to the drug sensitivity testing.