In the last decade we have witnessed a remarkable increase in the number of strains isolated in hospitals that are producing extended spectrum β-lactamases (ESBL) or, more recently, carbapenemases. This makes clear the need for a system for rapid detection of these resistance mechanisms that allow the selection of the most suitable antibiotic treatment in order to improve patient care. Recent data support the possibility of using mass spectrometry (MS), specifically MALDI -TOF (Matrix-Assisted Laser Desorption / Ionization, Time-of-Flight ) systems to identify specific resistance mechanisms and their use offers several advantages. First, the economic cost of each determination is clearly inferior to the classical molecular techniques for detection of resistance genes. Second, detection of resistance by MALDI -TOF reduces the time for obtaining results compared to the routine methods currently employed. Finally, the possibility that this method allows us to detect enzymes not previously characterized, that there is no information about the genes that encode them. Therefore, we believe that this may be a good tool to implement in clinical microbiology laboratories. This review aims to present the latest developments in this field.