This study was conducted to evaluate the effect of dietary supplementation of dairy cows with yeast culture (YC) on immune transfer to their calves during first days after birth and on some blood constituents of calves from birth to 15 wk of age. Total of 15 Friesian cows (weighing 500-520 kg and 2-4 parities) and 15 Friesian heifers (weighing 400-420 kg) at late pregnancy (3 mo pre-partum) were used in this study. All experimental animals were randomly allocated in randomized design to three experimental groups (n=10, 5 cows and 5 heifers in each), fed on the same diet. Animals in 1^st group were without treatment, while those in the second (T2) and third (T3) groups were orally administrated with 20 and 40 g/h commercial yeast culture (Thepax) for 90 days pre-partum and 90 days post-partum. After parturition, newborn calves were fed on colostrums of their dams, and then suckled milk up to weaning (105 d of age). Blood samples were collected from all newborn calves at first, second and third day after birth, then at 4, 8, 12 and 15 weeks of age. Hematological parameters including count of red (RBCs) and white (WBCs) blood cells, hemoglobin (Hb) concentration and packed cell volume (PCV) were determined in the whole blood. Concentration of total proteins (TP), albumin (AL), globulin (GL), total lipids (TL), cholesterol (CH), glucose (GLU), creatinine (CR), and thyroid hormone (T₃) as well as AST and ALT activities were determined in blood serum. Results showed insignificant effect of dam parity (cows and heifers) on count of WBCs, Hb concentration and PCV value in the whole blood, serum concentration of immunoglobulines (IgG, IgM and IgA), TP, AL, GL, GLU, CR and T₃, and ALT activity in serum of calves. Concentration of TL and CH, and AST activity were higher, while count of RBCs was lower (P<0.05) in calves of heifers than in those of cows. Concentrations of IgG, IgM and IgA were higher (P<0.05) in calves of T3 than in T1 by 32, 81 and 112%, respectively. Count of RBCs, Hb concentration and PCV value, and concentration of TP, AL and GL (P<0.05) and WBCs (P≥0.05) were higher in calves of T3 than in those of T1 and T2. Calves of T3 showed the highest (P<0.05) concentration of TL, CH and GLU and the lowest CR concentration and AST and ALT activity (P<0.05). Concentration of T₃ was lower (P<0.05) in T2 and T3 than in T1. Concentration of IgG, IgM and IgA in serum and WBCs count of calves decreased (P≥0.05) on the 3^rd day after birth. Count of RBCs, Hb concentration and PCV value increased (P<0.05) by advancing post-calving week.  Only, TP, AL, TL, CH, GLU, CR and T₃ concentrations and activity of AST and ALT showed different trends of changes by advancing post-calving week (P<0.05).In conclusion, pre- and post-partum yeast culture treatment at a level of 40 g/h/day for heifers and cows is able to enhance their newborn immunity response and improve calf performance with good health status, which allow for raising good male calves of breeding or female calves of milk production.