Hydropericardium syndrome (HPS), known as Leechi disease, is caused by Avian Adenovirus 4. HPS has been responsible for high mortality ranging from 60 to 70% among broiler breeds of 2 to 6 week age. The disease has been reported from Pakistan (1988), North and South Americas (1992), Mexico (1990), Iraq (1991), Australia (1992) and India (1994). The clinical cases of HPS exhibit large quantity of clear straw colored fluid in the pericardial sac, swollen and enlarged liver, reduced packed cell volume of blood, pronounced anemia, decreased ESR and albumin and tumefication of kidneys with sistended tubules. A commercial killed vaccine for IBH/HPS has been produced in Mexico. In India inactivated autogenous experimental vaccines have been claimed to show sometimes good results in field trials.