Endocarditis caused by non-HACEK gram-negative bacteria are very rare. However, it is more and more often reported as a nosocomial problem. This is especially serious because of the spread of multidrug resistant micro-organisms. Here we report the case of two patients who were admitted in our hospital for non-traumatic reasons and who were not affected by chronic diseases. We aimed at raising attention on an old but new threat: endocarditis caused by Klebsiella pneumoniae carbapenemase-producing and its possible treatment.