Background: Hydropericardium hepatitis syndrome (HHS) is an important emerging disease having economic importance and affecting particularly broiler chickens. Although the disease has been reported as a major problem in almost all the regions of India, not much is known from the North Eastern states of India. The present study was aimed to study prevalence, clinico-pathology and molecular diagnosis of HHS in poultry population of Mizoram. Methods: A poultry population of total 2430 from 15 different farms located in different districts of Mizoram were studied for outbreaks of HHS. Clinical manifestation of the disease in affected birds was recorded and pathological studies were carried out in total 190 dead birds. The outbreaks were further confirmed by detection of hexon gene of FAdV in tissue lesions by PCR. Result: Outbreak of HHS was recorded in 5 (33.3%) different broiler farms with sudden onset of mortality (18 to 25.2%) in broiler birds of 4 to 6 weeks of age. Pathological studies revealed characteristic lesions comprising hydro pericardium, hepatitis and basophilic intranuclear inclusion bodies in hepatocytes. Detection of hexon gene of FAdV in tissue lesions by PCR assay has further confirmed the outbreaks. This study reports for the first time, high prevalence of HHS in poultry population of Mizoram.