AIM To assess the burden of norovirus(No V) and to determine the diversity of circulating strains among hospitalized children in Lebanon. METHODS Stool samples were collected from children presenting with acute gastroenteritis to six major hospitals in Lebanon. A total of 739 eligible stool samples, testing negative for diarrhea caused by rotavirus as a possible viral pathogen, were collected between January 2011 and June 2013. A standardized questionnaire including demographic, epidemiological and clinical observations was used at the time of hospitalization of children presenting with diarrhea. Viral RNA was extracted from stool samples followed by reverse transcription polymerase chain reaction and nucleotide sequencing of a fragment of the viral protein 1 capsid gene. Multiple sequence alignments were carried out and phylogenetic trees were constructed using the MEGA 6 software.RESULTS Overall, 11.2% of stool samples collected from children aged < 5 years tested positive for No V genogroups Ⅰ(GⅠ) and Ⅱ(GⅡ). GⅡ accounted for 10.6% of the gastroenteritis cases with only five samples being positive for GⅠ(0.7%). The majority of hospitalized children showed symptoms of diarrhea, dehydration, vomiting and fever. Upon sequencing of positive samples and based on their clustering in the phylogenetic tree, 4/5 of GⅠ gastroenteritis cases were designated GⅠ.3 and one case as GⅠ.4. GⅡ.4 was predominantly detected in stool of our study participants(68%). We report a JB-15/KOR/2008 GⅡ.4 Apeldoorn 2008-like variant strain circulating in 2011; this strain was replaced between 2012 and 2013 by a variant sharing homology with the Sydney/NSW0514/2012/AUS GⅡ.4 Sydney 2012 and Sydney 2012/FRA GⅡ.4 strains. We also report the co-circulation of non-GⅡ.4 genotypes among hospitalized children. Our data show that No V gastroenteritis can occur throughout the year with the highest number of cases detected during the hot months.CONCLUSION The majority of No V-associated viral gastroenteritis cases among our participants are attributable to GⅡ.4, which is compatible with results reported worldwide. AIM To assess the burden of norovirus (No V) and determine the diversity of norovirus (No V) and to determine the diversity of circulating among hospitalized children in Lebanon. METHODS Stool samples were collected from children presenting with acute gastroenteritis to Six major hospitals in Lebanon. A total of 739 eligible stool samples , testing negative for diarrhea caused by rotavirus as a possible viral pathogen, were collected between January 2011 and June 2013. Amin questionnaire including demographic, epidemiological and clinical observations was used at the time of hospitalization of children presenting with diarrhea. from stool samples followed by reverse transcription polymerase chain reaction and nucleotide sequencing of a fragment of the viral protein 1 capsid gene. Multiple sequence alignments were carried out and phylogenetic trees were constructed using the MEGA 6 software. RESULTS Overall, 11.2% of stool samples collected from children aged <5 years tested positive for No V g G II accounted for 10.6% of the gastroenteritis cases with only five samples being positive for GⅠ (0.7%). The majority of hospitalized children showed symptoms of diarrhea, dehydration, vomiting and fever. Upon sequencing of positive samples and based on their clustering in the phylogenetic tree, 4/5 of GI gastroenteritis cases were designated GI.3 and one case as GI.4. GII.4 was predominantly detected in stool of our study participants (68%) . We report a JB-15 / KOR / 2008 GⅡ.4 Apeldoorn 2008-like variant strain circulating in 2011; this strain was replaced between 2012 and 2013 by a variant sharing homology with the Sydney / NSW0514 / 2012 / AUS GⅡ.4 Sydney 2012 and Sydney 2012 / FRA G Ⅱ .4 We also report the co-circulation of non-GⅡ.4 genotypes among hospitalized children. Our data show that No V gastroenteritis can occur throughout the year with the highest number of cases detected during the hot months.CONCLUSION The majority of No Va ssociated viral gastroenteritis cases among our participants are to to GⅡ.4, which is compatible with results reported worldwide.