Subclinical mastitis is one of the most important diseases affecting farm animals causing economic losses. So, the present study was designed to determine the effect of vitamin E and selenium treatment on subclinical mastitis and to find the relationship between clinicobiochemical changes in mastitis in subclinical mastitic buffaloes. The present study was carried out on thirty lactating buffaloes, aged between 4-6 years, belonging to some private dairy farms in Sharkia governorate. The animals were divided into 3 equal groups. Group I: consisting of 10 healthy animals. Group II and III, ten buffaloes in each, were positive for intra mammary mastitis infection. Group II buffaloes treated only with Enrofloxacin for five days, while those of group III received combined treatment with Enrofloxacin and Vitamin E plus selenium for five days by intramuscular route. Milk and blood samples were collected just before treatment, 3, 8 and 15 day post treatment. The prevalence of subclinical mastitis in examined animals was 44.89 % of examined quarter milk samples. The bacteriological examination of milk samples revealed isolation of 4 types of bacteria: E coli (36.36%), Staphylococcus aureus (20.45%), Streptococcus dysagalactiae (11.36%) and Pseudomonas aerugenosa (4.54%). The mixed infections were Staphylococus aureus with E. coli (18.18%), Streptococcus dysagalactia with E. coli (9.09%). The results of this study showed that phagocytic activity and phagocytic index in milk were significantly lower in mastitic buffaloes before treatment compared with healthy ones. The blood picture revealed that, buffaloes suffering from subclinical mastitis showed anemia associated with significant increase in total leukocytic count with neutrophilia, lymphopenia and eosinopenia in addition to highly significant increase in E.S.R. Concerning the serum mineral profiles, of mastitic buffaloes before treatment, there was no significant difference in serum concentration of sodium between mastitic and control buffaloes. However, there was a significant decrease in calcium and potassium level in mastitic animals. The results also, showed that cortisol, total sialic acid (TSA) and lipid bound sialic acid (LBSA) were significantly higher in subclinical mastitis group compared with control (P<0.001). Protein bound sialic acid did not change in subclinical mastitis in comparison with control group. In the current study, our data indicated reduction of SCC, enhancement cellular defense mechanism of the diseased mammary gland in animals of group III treated with Enrofloxacin and Vitamin E plus selenium as compared to the Enrofloxacin treatment alone. Most of studied hematological, biochemical and inflammatory markers returned to their normal range by the end of the experimental period. However, the cure rates of animals in group III was faster and more pronounced than group II. Hence Vitamin E plus selenium therapy may be added along with the antibiotics for effective amelioration of intramammary infection in buffaloes.