The present study was conducted for the phenotyping of antibiotic resistance patterns among patients infected with Klebsiella pneumoniae, isolated from different clinical sites of the patients admitted to the Medical City Teaching Laboratories in Baghdad, Iraq, and to study the frequencies of the blaCTX-M, blaTEM, and blaOXA genes in the extended-spectrum b-lactamase (ESBL)-producing isolates. A total of 20 out of 35 (57.14%) K. pneumoniae isolates collected from different clinical samples were identified as ESBL producers using the combination disk test (CDT) against six types of antibiotics, as suggested by the Clinical and Laboratory Standards Institute. All K. pneumoniae isolates were observed for ESBL positivity using the CDT method and screened for blaTEM, blaCTX-M, and blaOXA genes by PCR using a specific primer. In total, 19/20 (95.0%) ESBL-positive isolates harbored the TEM genes, 18/20 (90.0%) carried CTX-M, while the blaOXA gene, for the first time in Baghdad city, was not reported in any of the isolates. A high occurrence of ESBL-producing K. pneumoniae was observed in our study based on the analysis of the TEM and CTX-M genes. Although molecular methods are more reliable in identifying ESBL production, routine clinical screening for ESBL-producing K. pneumoniae by phenotypic methods, such as CDT tests, must be introduced and encouraged in clinical settings because of its low cost.