Background: Hypervirulent Klebsiella pneumoniae (hvKp) is an emerging pathogen causing life threatening infections. There are different determinants of virulence for these phenotypes like biofilm formation, large capsule, and siderophores. Many genes regulate these determinants as rmpA and rmpA2. Aim of the work: This study aims to detect the antimicrobial resistance profile, biofilm formation, and association between rmpA with hypermucoviscosity and biofilm formation among hypermucoviscous K. pneumoniae (hmvKp) isolates.  Material and Methods: Eighty Klebsiella pneumoniae (K. pneumoniae) isolates were collected from main microbiology laboratory of   Ain Shams University Hospitals then subjected to phenotypic identification, antimicrobial susceptibility testing, biofilm formation ability, and detection of rmpA gene by PCR. Results: Eighty K. pneumoniae clinical isolates were tested, most of them were from sputum 30/80 (37.5%). 37/80 (46.25%) isolates were identified phenotypically as hmvKp by string test while classic K. pneumoniae (cKp) were 43/80 (53.75%). Biofilm formation was higher among hmvkp isolates than ckp A statistically significant difference of rmpA gene distribution among K. pneumoniae phenotypes were detected, the gene was detected in 31/37(83.8%) of hmvKp isolates, and in 5/43(11.6%) of cKp isolates respectively. Considering PCR as the gold standard, on comparing string test results with rmpA gene results, the sensitivity and the specificity of string were 86.11% and 86.36% respectively. Conclusion: HmvKp is being increased among K. pneumoniae clinical isolates with high rate of biofilm formation. The string test is a simple and rapid screening test of hmvKp that compared with detection of rmpA gene as a confirmatory tool for hypermucoviscosity.