The correlation between the phenotypic and the genotypic pattern of aminoglycosides resistance was studied in 396 gram negative bacilli isolated from 1559 urine samples collected in Kaser-El- Eini hospital from March 2008 till June 2008, 45 isolates were resistant to aminoglycosides, armA was detected in 7 isolates (6 Klebsiella spp,1 E coli) and rmtB was detected in 5 isolates (3 Klebsiella spp,2 E coli ), all armA and rmtB positive isolates were resistant to Floroquinilones and were extended spectrum β-lactamases producers, further studies of the other 16 S rRNA methylases genes and applications of proper infection control measures are recommended.