The effect of velogenic Newcastle disease virus (vNDV) on the immune responses and serum proteins was investigated in six-week-old ducks and chickens. Results showed that weight loss was markedly significant (p < 0.05) from days 3 -21 (PI) in chickens and mild (p < 0.05) on days 3 and 15 PI in ducks. The antibody response obtained showed significant (p < 0.05) increase in infected chickens (IC) than those of the infected ducks (ID). While the total serum protein and serum globulin increased significantly (p < 0.05) in IC on days 7 and 14 PI, they decreased significantly (p < 0.05) in ID only on day 21 PI. The immune responses and serum protein values in this experiment X-ray showed less susceptibility of ducks when compared with the chickens. This may be related to marked anorexia and severe dehydration observed in the latter consequent upon serum concentration. Ducks could be maintaining the endemicity of Newcastle disease (ND) as reservoir host.