Protoplast fusion between L. casei KCTC 1121 and L. acidophilus 88 was attempted to obtain improved strains. The fusants produced a bacteriocin against indicator strains, making a smaller inhibition zone compared to that of L. acidophilus 88. After culturing for 2 months on selective medium, the selected fusants were still stable without segregation. Fusants showed higher lipase activity compared to those of the two parent strains. Fusant No.4, 11, and 15 exhibited excellent lactic acid productivity. Fusant No.4 and 15 exhibited improved proteolysis ability compared to the two parent strains. Whereas L. casei possessed both ${eta}-galactosidase$ and $phospho-{eta}-galactosidase$ activities, and L. acidophilus 88 had only ${eta}-galactosidase$ activity, the fusants had both the intermediate enzyme activities. Cell size of the fusants was greater than that of the parents.