Objective:To delineate the frequency of occurrence ofblaCTX-M,blaTEM, andblaSHV in Enterobacteriaceae from North-Indian tertiary hospital.Methods: A random collection of a subset of45Escherichia coli (E. coli) and28Klebsiella pneumoniae (K. pneumoniae) that was resistant to a third generation cephalosporin and obtained during2007-2008 was selected for detailed screening forblaCTX-M,blaTEM, andblaSHV by monoplexPCRs. The isolates demonstrating the presence of blaCTX-M alleles were characterized for the specificCTX-M-genogroup by using a multiplexPCR.Results:Resistance to cefoperazone, ceftazidime, ceftriaxone, cefotaxime, cefoxitin and piperacillin was 100% each inK. pneumoniae isolates, whereas these resistance-rates forE. coli isolates were93.1%, 83.8%, 91.9%, 93.6%, 97.3% and97.1%, respectively. Concomitant resistance to aminoglycosides, quinolones and aztreonam was also noticed. Presence of any of the bla genes (blaCTX-M,blaTEM, andblaSHV) was noticed in a total of28 (38.4%) isolates of the73isolates studied. Many isolates demonstrated occurrence of these genes in various combinations.blaCTX-M,blaTEM, andblaSHV were noticed in 28.8%,10.9% and13.7% isolates, respectively. MultiplexPCR inblaCTX-Mharboring isolates demonstrated the presence ofCTX-M-Genogroup-1 and sequencing for the specificCTX-M-type revealed presence ofCTX-M-15 type. RAPD typing showed wide diversity in isolates.Conclusions:This is amongst the premier report describing the simultaneous occurrence ofblaTEM,blaSHV, andblaampC in IndianEnterobacteriaceae and that wider dissemination of these genes, as demonstrated by diversity of isolates, raises conc and emphasizes a need for extensive search for the presence of these gene pools in Indian subcontinent.