An experiment was conducted to study the effects of different oil sources on performance, serum lipoproteins, antibody titre, histology and fat accumulation in broiler chicks. In a completely randomized design, 320 one-day-old broiler chickens (Ross 308) were randomly allocated to four dietary treatments viz., 1) diet without oil as control, 2) diet with fish oil, 3) diet with soybean oil and 4) diet with olive oil at the rate of 2.15% in the starter and 3% in the grower and finisher diet. The results showed that the broilers fed diet containing soybean oil had better feed conversion ratio (FCR) in grower and finisher period (P<0.05). At day 42 of age, antibody titre against Newcastle in chicks fed a diet containing fish oil was higher than the other groups without affecting immunity against sheep red blood cells (SRBC). Effects of different sources of oil on histological studies of liver showed lower lipid deposition in birds fed fish oil in comparison with other treatments. The lymphocytes proliferation in Bursa of Fabricius was more with central nucleus than the other treatments. These results suggested that addition of fish oil to the poultry diet resulted in improved immune response while soybean oil enhanced the performance.