To evaluate the effect of 4 different levels of propolis supplementation on the hematological and immunological parameters of laying hens, a trial was conducted with 60 White Leghorn layer hens. The experiment was conducted by using a randomized design with 5 treatments, 4 replicates, and 3 hens in each replicate. Treatments included basal diet (control) and basal diet plus 0.5, 1, 3, and 6 g of propolis/kg of diet, respectively. At the end of the 12-wk treatment period, samples of blood were collected to determine hematological and immunological values. The results showed that the addition of propolis at 3 g/kg in the diet resulted in significant increases (P < 0.05) in the serum IgG and IgM levels and significant decreases (P < 0.05) in the peripheral blood T-lymphocyte percentage compared with those of the control and other treatment groups. In addition, the level of 3 g/kg of propolis supplementation significantly increased (P < 0.05) erythrocyte count (red blood cells) compared with the other treatments. On the other hand, hemoglobin and hematocrit values and total leucocyte (white blood cells) and differential leucocytes counts were not influenced by propolis supplementation. These results indicate that the inclusion of propolis at the level of 3 g/kg of diet may have a positive effect on humoral immunity of laying hens.