The aim of our study is to evaluate the effect of Apsa-mos ® as immunostimulant on the level of antibodies in broiler chickens vaccinated with Newcastle disease live attenuated vaccine (β1 and lasota strain) at 10, 24-day old respectively. Forty, one-day-old chicks were reared in this experiment. They were divide into four groups and treated as follows: Chicks in the 1st group were treated as control one (G1); Chicks in the group 2 (G2), were vaccinated with live attenuated β1 NDV vaccine at 10 days followed by attenuated lasota NDV strain vaccine at 24 days of age, chicks in the group three (G3) were vaccinated as in group 2 but amended with Apsa-mos ® at a rate of 1 mg / kg of feed; Chicks in the 4th treatment was given Apsa-mos ® only at a rate of 1 mg / kg of feed. Antibody titers after administration of NDV vaccines were estimated using ELISA technique. The results showed a significant difference in the titers between the vaccinated and non-vaccinated birds with higher values when Apsa-mose ® was added, in comparison with groups 1 and 4. No significant changes were noticed between granulocytes differential counts and in the values of stress factor of heterophiles/lymphocytes (H/L ratio) in all treated groups. Amending Apsa-mos ® to the feeds of the treated birds G3 and G4 has no negative effect on the treated and play a positive role by restoring the normal architecture of lymphoid tissues of bursa of Fabrecious and caecal tonsils. We concluded that the giving of Apsa-mos improve the immune state of the chicks in both types humeral and cellular immunity especially in G3 and decreased the influence of the vaccine in this group and increase the immunity in G4 also Apsa-mos decrease the effect of the vaccine in G3 seen in histological changes in bursa of fabricious and cecal tonsils.