Human bocavirus (hBoV) was first discovered in respiratory samples from children in 2005, and has been classified in the Parvoviridae family. hBoV has also been detected in children with acute gastroenteritis. This study was performed to analyze the frequency and phylogeny of hBoV in the respiratory and stool samples of children with acute respiratory tract illnesses and gastroenteritis during the time period beginning 2006 and ending 2008, at the Virology Research Centre, Masih Daneshvari Hospital, NRITLD, Tehran, Iran. Respiratory and stool samples were screened for hBoV by nested polymerase chain reaction with primers from the NS-1 gene. Nine out of 133 respiratory samples (6.8%) and 6 out of 47 stool samples (12.8%) were positive for hBoV. Ten positive samples (7 respiratory and 3 stool samples) were subjected to phylogenetic analysis by sequencing a fragment of the VP1/VP2 gene junction. The results showed a high similarity among isolates (>or=99%). It was found that hBoV isolates can be divided into 3 genetic groups.