Carbapenems play an important role in the treatment of nosocomial infections caused by Pseudomonas aeruginosa. Resistance to carbapenem is often due to loss of outer membrane protein, expression of efflux system, or production of metallo-beta-lactamases (MBLs). Our purpose was to search for MBL producing bacteria, because in this country there haven’t been done any studies considering the occurence of this phenomenon. Materials and methods: We have analysed 37 P. aeruginosa isolates from the Microbiological Laboratory of Clinical County Hospital Tg Mures between October 2005 - February 2006. A double-disc screen test was used for the detection of MBLs using imipenem discs (10 μg) alone and in combination with EDTA (2mM ). The difference in zone diameters should be more than 2mm to consider this test as a positive one. The method is based on the ability of EDTA to inhibit the activity of MBLs. Results: None of the 37 isolates proved to be MBLproducer. Conclusions: The uncontrolled spread of MBL producing strains may lead to treatment failures. As early detection of these isolates is essential, all of imipenem-nonsusceptible isolates should be screened for this resistance phenotype.