Avian adenovirus was isolated from naturally infected birds during 1990 to 2003 in the vicinity ofKarachi, Pakistan. The virus is known to cause hydro-pericardium syndrome (HPS) in poultry. The mortalitywas recorded 20-50% in commercial broilers. Fifty field samples were collected; however, six samples wereselected for molecular studies. These isolates were grown and characterized by cell cultu...