The objective of the present study was to evaluate the biochemical effect of betaine administration on bird performance after an experimental coccidial infection in broilers. Two hundred and fifty one day old Cobb broiler chicks were divided into 5 groups with different supplementations. Three groups are infected with 30000 E. tenella sporulated oocysts/chick. Blood samples were collected twice at age of 20 and 30 days of chicks for liver function evaluation then birds were sacrificed and livers were collected for histopathology. Results revealed that coccidiosis caused a significant increase in serum (AST, total cholesterol, triacylglycerols, VLDL, cortisol & CRP) and a significant decrease in serum TP, Albumin & LDL. Supplementation of betaine to infected group exhibited a significant decrease in serum level of (AST, ALP, total cholesterol, triacylglycerol, VLDL, cortisol & CRP) and a significant increase in serum TP, albumin and LDL activity after 3 days of the 1st and 2nd treatment doses when compared with untreated-infected group. In conclusion, Administration of betaine with coccidiosis caused significant improvement of all biochemical parameters, betaine has a protective effect against coccidiosis induced liver damage and oxidative stress in chicken so lead to increased body weight.