The present study was conducted to compare the biochemical and histopathological changes in response to pathogenic field infectious bursal disease virus (IBDV). The Bursa of fabricius was collected from poultry flocks of Punjab Pakistan for isolation of IBD virus by inoculating in embryonated chicken eggs through chorioallantoic membrane. The two hundred birds were divided into 4 groups A, B, C and D). The birds in group A were commercial broiler chicks having maternal derived antibodies and were challenged with IBDV field isolate at the rate of 0.1ml of EID50 (virus titer 105.50/100μl) on 2nd week of age through eye drops. Group B specific antibody negative (SAN) chicks were challenged with same dose at 2nd week of age. While the group C and D was unchallenged control containing commercial and SAN chicks. The Blood samples were collected from group A, B, C and D on 3rd, 5th and 7th day of post infection for biochemical analysis. The Albumin and total protein values were significantly low (P<0.05) in infected groups A and B as compared to control groups C and D on 5th and 7th day. The alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were significantly (P<0.05) high in infected groups A and B. On 3rd, 5th and 9th day five birds from each group were slaughtered and histopathological lesions observed in bursa, spleen and thymus and compared with control. Mild to severe hemorrhages and lymphocytic depletion, follicle necrosis, leukocytic infiltration, cyst formation and fibrous tissue proliferation at medullar region of thymus and bursa were observed. These results indicated that pathogenic field IBDV caused the serum biochemical changes by damaging the liver and kidney tissues with histopathological effect on lymphoid organs of chicken.