Klebsiella pneumoniae (KP) is the most common cause of neonatal sepsis in the low-and middle-income countries. Our objective was to describe the phenotypic and molecular characteristics of extended-spectrum â-lactamase (ESBL)-producer KP in neonatal care centers from Peru. We collected 176 non-duplicate consecutive KP isolates from blood isolates of neonates from eight general public hospitals of Lima, Peru. The overall rate of ESBL production was 73.3% (N = 129). The resistance rates were higher among ESBL-producer isolates when compared with the nonproducers: 85.3% versus 12.8% for gentamicin (P < 0.01), 59.7% versus 8.5% for trimethoprim-sulfamethoxazole (P < 0.01), 45.0% versus 8.5% for ciprofloxacin (P < 0.01), and 36.4% versus 12.8% for amikacin (P < 0.01). A total of 359 â-lactamase-encoding genes were detected among 129 ESBL-producer isolates; 109 isolates (84.5%) carried two or more genes. Among 37 ESBL-producer isolates randomly selected, CTX-M-15 and CTX-M-2 were the most common ESBLs detected. Most of the isolates (92%) belonged to the group KpI. Pulsed-field gel electrophoresis showed that multiple KP clones were circulating among the eight neonatal units included.