The extent of allergenicity of whey protein was revealed by inhibition ELISA using blood serum obtained from milk allergic infants. The effect of in vitro proteolysis on allergenicity and development of bitterness was studied using enzymes individually and in combination. Selective proteolysis of WPC was done to 3 and 5 per cent DH. A combination of enzymes was effective in reducing allergenicity at a lower DH. Sensory evaluation of hydrolysates was done to give bitterness scores. A hydrolysate with minimum bitterness and maximum reduction in allergenicity could be used to develop an ingredient for hypoallergenic cow milk formula.