Yeast culture additive product (Alpha Yea Mix ®) was offered to 4 multiparous lactating buffaloe through 4x4 Latin Square design. Buffalo's with 591± Kg average weigh,   ± Kg average milk yield, 70 DIM and 3-4 lactation seasons. The study aimed to investigate the effect of yeast culture supplementation on nutrients digestion, milk yield and constituents of buffaloes. Each experimental period lasted for 30 days. By the end of each period fecal grab samples for successive three days and milk samples for successive five days  were collected and anlyized. Results obtained indicated that DM, OM, NFE, ADL and hemicelluolose digestibilities were not changd among different supplemnted diets. Crude protein (CP) and ether extract (EE) digestibilities tended to be insignificantly higer for buffaloes fed 30 and 40 g/h/d of yeast culture. Crude fiber (CF) and its fractions digestibility, including NDF, ADF and celluolose were significantly increased (10 - 22 %) in buffaloes fed 30 and 40 g/h/d of yeast comparing with those fed the control and 20g yeast. Diet feeding value expressed as TDN and DCP were insignificantly increased with buffaloes fed the higher levels of yeast supplementation. Actual milk yield, Kg/g was insignificatly increased with buffaloes fed 30 and 40 g/d of yeast culture. Milk constituents including fat percent and yield, protein percent and yield, lactose, urea, ash, TS, SNF percentages and somatic cell count (SCC) were not affected as a result of yeast culture supplementation to lactating buffalo's diets.  Milk constituents tended to be higher with buffaloes fed 20g/d yeast supplemented diet vs. the other diets. The basic economic measures explicit to cost / benefit analysis indicated that the milk net return over feeding cost was proportionaly higher as much as yeast culture supplementation increased in the diet. The implication of the present study is to add yeast culture products which mainly contain Saccharomyces cerevisiae (2x10⁹)/g at level of 30 – 40 g/h/d to improve milk yield and consequently the net revenue.