The impact of avian leukosis virus (ALV) on broiler production was evaluated using 300 chickens ofthe Ross 308 (75 male, 75 female) and Cobb Vantres (75 male, 75 female) lines. Cloacal swabs were taken from ali the birds at one day of age and tested for VLA using ELISA. A total of five birds from the Ross 308 line and four from Cobb Vantress lines tested positive and subsequently disseminated the virus. Based on results of the ELISA test, four experimental groups of 60 birds each were established. One group contained the Ross 308 line ALV positive males and females, another the Cobb Vantress ALV positive males and females, another the Ross 308 ALV negative males and females and the last, the Cobb Vantress ALV negative males and females. Ali birds were tested again for ALV by cloacal swab on days 28 and 49, and evaluated for weight, pigmentation and unifonnity. HorizontalALV infection did not significantly change the weight, pigmentation or unifonnity of effected birds.