Extended spectrum p-lactamases (ESBL) are capable of inhibiting the action of extended spectrum cephalosporins and monobactams. The objective of this work is to describe six isolates of ESBL producing Pseudomonas aeruginosa, retrieved from intensive care patients. The susceptibility test was performed by diffusion. For the phenotypic detection of ESBL, the following was assessed: the difference between ceftazidime ceftazidime/clavulanic acid (CAZ-CAC) and the synergy between imipenem-ceftazidime (IMI-CAZ) and cefepime-ceftazidime/clavulanic acid -ceftazidime (FEP-CAC-CAZ). The presence of metallo-ß-lactamases (MBL) was discarded through the double disc imipenem-EDTA/mercaptoacetic-meropenem (IMI-EDTA/SMA-MER) method. Molecular characterization of ESBL was performed by polimerase chain reaction (PCR) with blaGES primers. Synergy IMI-CAZ was observed in the studied strains; ESBL type GES was confirmed in five of them. The strategic location of the discs and the evaluation of alert signáis for the detection of ESBL is essential, thus contributing to the correct recommendation of treatment in the clinical report.