The purpose of this experiment was to produce a fermented whey beverage using a Lactobacillus strain DY1 obtained from bioprocess laboratory, Department of Biotechnology, Kathmandu University. Whey protein was concentrated using pH adjusted thermal precipitation technique, mixed with fruit juice and fermented using the lactobacillus strain. The blend of whey protein and juice was taken in various ratios and fermented for variable time. Ratio of whey protein : juice in 70:30 fermented for 16 hours gave the most promising characteristics. The product formed was good in taste, had appealing color, cfu of 107/ ml, pH of 4.0 and high in protein.