This study, was carried Out to determine the effects of probiotics based on Lactobacillus sp. (LB) or LB plus yeast (Saccharomyces cerevisiae) (LBY) on milk yield and composition of high yielding dairy cows in early lactation. Nine lactating cows were subjected to three dietary treatments, control cows were fed oil a diet without probiotic, LB cows were fed oil a diet supplemented with 450 mg/kg dominantly Lactobacillus sp. containing 2 x 10(8) cfu (Lactobacillus plantarum, L. bulgaricus. L. acidophilus, L rhamnosus, Bifidobacterium bifidum, Streptococcus thermophilus, Entercoccus faecium, Aspergillus oryza, Candida pintolopesii) per g and LBY cows were fed on a diet supplemented with 450 mg/kg mixture of LB containing 2 x 10(8) cfu and yeast cultures containing 2.25 x 10(9) Saccharomyces cerevisiae per g, based on 3 x 3 Latin Square Design with three replications each 21-d, Experimental diet was Formulated with 60:40 concentrate and alfalfa hay ratio to be isocaloric (10.0 MJ ME kg(-1) DM) and isonitrogenic (16.8% CP). Feed intake,. body-weight changes, milk yield and milk composition were determined during the study. The results showed that the probiotics based on either LB itself and its supplementation with yeast had no effect on milk yield and milk composition of high yielding dairy cows in early lactation.