Carbapenems (CARBs) are the primary treatment for infections caused by extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae strains. Production of a serine carbapenemase, KPC, is increasing alarmingly in the United States and is probably contributing to CARB resistance rates. We describe the clinical and molecular characteristics of four infections caused by KPC-3 K. pneumoniae strains.