Copper-nicotinic acid complex was fed as a food additive to baby chicks and their immune status estimated after vaccination with Hitchner B₁ and inactivated ND vaccines. This work was done in order to determine the immunostimulant effect of copper(I)-nicotinic acid complex in chickens. Immunity was estimated by haemagglutination inhibition, agar-gel precipitation, and challenge tests. Results showed much higher immunity status and post vaccination protection in birds supplemented with the complex. These data can be used in developing and realizing veterinary preventive programs or passive immunity in childhood.