Immunopotentiating activity of water extract of Lycii Fructus, Rubus Fructus, Torilis Fructus, Schizandrae Fructus and Cuscutae Semen were investigated using mouse fed with normal diet and protein deficient diet. Body weight, ratio of spleen or thymus to body weight, number of total peritoneal exudate cell, content of total serum protein and albumin content were decreased in the mouse fed with protein deficient diets as compared to the mouse fed with normal diet. Regardless of the nutritional condition, the supplement of the water extract of Lycii, Rubus Torilis, Schizandrae Fructus or Cuscutae Semen increased the ratio of spleen to body weight. The increment of this ratio was significant by the supplement of water extracts of Lycii and Torilis Fructus in mouse fed with protein deficient diet. The supplement of water extracts of Torilis Fructus to the mouse fed with protein deficient diet increased the content of total serum protein and albumin content significantly. Similar results were obtained with Lycii, Rubus, Schizandrae Fructus and Cuscutae Similar. The electrophorogram shows the difference in the concentration of some serum protein constituents between the mouse fed with normal diet and protein deficient diet.