The present study has been planned to study the pathogenicity of FAdv-4 by inoculation of different age groups of broiler birds through different parenteral routes and oronasal routes. The liver homogenate suspension prepared from infected liver samples and cell culture propagated infectious agents were used to infect the susceptible broiler birds via parenteral routes and through oronasal routes. For this purpose two experiments were designed as Experiment I and II. In Experiment I the 25-day-old broiler birds were inoculated with different dilutions of liver homogenate and cell culture propagated HPS virus through intramuscular (i/m) and oral routes. Similarly in Experiment II the one-day-old, 1-week-old, 2-week-old, 3-week-old and 4-week-old broiler chickens were inoculated with the original dilution (100) of same liver homogenate and cell culture propagated HPS virus through S/C and oral route. The birds were kept under observation for recording morbidity and mortality. In Experiment I the liver homogenate caused 64% mortality in broiler birds of the Group A through intramuscular route, while 33.33% mortality in broiler birds of Group B through oral route. The cell culture propagated HPS virus caused 60% and 13.33% mortality in broiler birds of Group C and D through intramuscular and oral routes, respectively. In Experiment II none of the day-old-chick died from Group A inoculated with liver homogenate and cell culture propagated HPS virus through s/c and oral route. The liver homogenate and cell culture propagated HPS virus caused high mortality in different age groups of broiler birds through s/c route than oral route. The blood samples were collected from the broiler birds before and after infection and various hematological parameters such as Hemoglobin and packed cell volumes were studied. The values of hemoglobin and packed cell volume showed highly significant (P<0.05) reduction indicating anaemia. The values of hemoglobin and packed cell volume of the broiler birds inoculated with infectious liver homogenate showed highly significant reduction than the birds inoculated with cell culture propagated HPS virus. The results indicated that the liver homogenate is more pathogenic than cell culture propagated HPS virus. There changes may be due to adoptability of the original FAdVs after continued passages in the culture of chicken embryo liver cells.