Aminoglycoside group antibiotics are commonly used especially in hospital-acquired infections. However, the resistance to these antibiotics is an important problem. In this study, 260 Gram-negative rods isolated in various clinical samples of hospitalized patients in the surgical and coronary intensive care units were evaluated. The most frequently isolated species were Pseudomonas aeruginosa (25.8%) and Klebsiella pneumoniae (25.8), followed by Acinetobacter baumannii (19.2%). The susceptibility rates to aminoglycosides of the rods, determined using E-test, were 73.4% for isepamicin, 65.3% for amikacin and 56.5% for gentamicin. In conclusion, isepamicin was the most effective aminoglycoside against Gram-negative rods whereas the resistance to isepamicin was significant.