The aim of work was to utilize the by-products such as whey or milk permeate to produce single cell protein and to reduce the environmental pollution from three individual yeast strains (Kluyveromyces fraglis, Kluyveromyces lactis or Saccharomyces cervesiae). All of these were cultivated at the optimum condition for 48 and 96 hr by using whey, permeate or YM as media. The obtained results indicated that Kluyveromyces fraglis achieved the highest growth (22 x 10⁶ cfu/ml) on the whey after 96 hr, and the yield of biomass (2.5 gm/L) after 96 hr., followed by Kluyveromyces lactis and Saccharomyces cervesiae. K. fraglis achieved the highest value of BOD (58.1 mg/L) on the permeate after 96 hr, and the removal and consumed lactose (37 %) on permeate after 96 hr.