The aim of study was to evaluate the effect of BCS and selenium-vitamin E supplementation on milk yield and composition, blood parameters and metabolic diseases in high producing Holstein cows. The experiment was coducted as a completely randomized design with 2*2 factorial method. Total 136 multiparous cows at the beginning of transition period to 3 months after calving were used in this expriment. Treatments were 1) body condition score 4 with injection selenium-vitamin E 2) body condition score 4 without injection selenium-vitamin E 3) body condition score 3.5 with injection selenium-vitamin E 4) body condition score 3.5 without injection selenium-vitamin E. BCS were measured using ultrasonography and by individual observation in 3 weeks intervals. Blood samples were taken from the coccegeal vein at parturition time and weeks 2, 4 and 6 of postpartum period. Disease incidence was assessed by examining the symptoms and diagnosis of farm veterinarian. Production and milk composition in the form of monthly records were obtained in the first 6 months of lactation. The results showed that cows with a body condition score 4 had higher (P 0.05) milk production than those the other treatments. The treatment which received selenium-vitamin E had higher (P 0.05) fat to protein ratio in milk. The animals receiving selenium-vitamin E had higher (P 0.01) total serum protein and albumin levels. Rectal temperature was higher (P 0.05) in cows with normal BCS 2 weeks after parturition. Our treatment had no effect on the uterus involution. Injection of selenium-vitamin E improved the health status of animals; however the supplementation had no significant effect on the incidence of disease. Keywords : body condition score, selenium-vitamin E, metabolic diseases, blood parameters