Background: Hypervirulent Klebsiella pneumoniae (K. pneumoniae), generally associated with the hypermucoviscous phenotype has emerged as a clinically significant pathogen responsible for serious disseminated infections, such as pyogenic liver abscesses, osteomyelitis, and endophthalmitis, in a generally younger and healthier population. The aim of this study was to investigate the molecular characterization of hypervirulent (hypermucoviscous) K. pneumoniae strains, which mainly emerged in EGYPT. Methods: Bacterial species were identified by standard methods with a VITEK 2 compact system. The serotyping, biotyping and the String test for phenotypic detection of mucoviscosity were used. Antimicrobial susceptibility to several commonly used antibiotics were determined by the Kirby-Bauer's disc diffusion method according to the Clinical and Laboratory Standards Institute (CLSI, 2018). Polymerase chain reaction (PCR) was used to amplify virulence-associated genes (rmpA, magA, entB, and iucA). Results: One-hundred isolates of each hypervirulent K. pneumoniae (hvKP) and classical K. pneumoniae (cKP) were screened over a 2-year period. The serotyping showed that 76 isolates had K1-type while 19 had K2-type of capsule and 5 non-K1/K2 isolates of hvKP while for cKP, only 3% was K1, 1% K2 and 96% were non k1/K2. Among the hvKP isolates, the prevalence of virulence associated-genes as rmpA gene was 93% and for magA gene was 40% and for iucA 92%. Otherwards, the prevalence of these genes in cKP isolates was very low 11%, 7% and 0%, respectively. However, there was no significant difference for entB (89 % and 92 %). Conclusion: The hypervirulent isolates were infrequent among K. pneumoniae isolates causing bacteremia in our geographical area (El-Mansoura, Egypt). For good understanding the basic biology of hypervirulent K. pneumoniae, this study summarized and focused on epidemiology, hypervirulence-associated factors, and antimicrobial resistance mechanisms of such hypervirulent strains. This epidemiological study give alarm about the dissemination of hypervirulent K. pneumoniae strains. Therefore, an immediate response to recognize these hypervirulent strains with resistance determinants is an urgent priority.