The purpose of the present study was to comparatively investigate the effect of Avilamycin and Immunowall on the improvement of humoral immunity in boiler chickens. In this study, 360 cobb broiler chickens were divided into three similar groups of 120 chickens with four replicates of 30 chickens in each group. In the first and second experimental groups, 1 kg/ton of Immunowall and Avilamycin respectively were added to the basic diet while in the third control group only the basic diet was used. On days 9, 17 and 25 of the breeding period (corresponding to 1 day before and 7 and 14 days after the first Newcastle B1 vaccination), 40 chickens were randomly chosen in each experimental group, their blood samples collected, and then serum antibody titres of these chickens against the Newcastle vaccine were measured by HI test. After stastistical analysis using ANOVA and Duncans’s multiple range test, the results of serum antibody titres by HI test on day 9 of the breeding period was not statistically significant. The results of HI test on day 17 of the breeding period (5.01 ± 0.32, 5.27 ± 0.27 and 5.13 ± 0.20 in the control and experimental groups 1 and 2 respectively) was also statistically not significant. The HI test results on day 25 of the breeding period (5.04 ± 0.44, 5.87 ± 0.47 and 5.61 ± 0.41 in the control and experimental groups 1 and 2 respectively) indicated significant statistical differences (P