Extensive use of antimicrobials such as aminoglycosides has been associated with increasing antimicrobial resistance. The aim of present study was to investigate prevalence of aminoglycoside resistance and frequency of resistance genes aac(3)-IIa and aac(6’)-Ib involved in resistance of Klebsiella pneumoniae to aminoglycosides. 212 clinical strains of K. pneumoniae isolated from Urmia hospitals collected from May 2013 to January 2014 were assessed in the study. The Kirby-Bauer method was used for screening of resistant isolates to Gentamicin, Amikacin, Kanamycin, Tobramycin and Netilmicin. The aac(6’)-Ib and aac(3)-IIa genes were amplified by PCR method. Among 212 K. pneumoniae isolates evaluated, the most resistance rate observed against Gentamicin (26.9%). In total, 85 (40.1%) were resistant at least for one of aminoglycosides used. Among bacteria with resistance or intermediate susceptibility to aminoglycoside, 62(72/9%) and 63(74/1%) of isolates had acc(3)-IIa and aac(6’)-Ib genes respectively. Our study showed that aminoglycoside resistance rate in klebsiella isolated from hospitals in northwest of Iran (Urmia) is relatively high and acetyl transferase modifying enzymes have the major role in resistance.