The feeding trials have been conducted to study the requirements and deficiency symptoms of young carp for riboflavin and pantothenic acid. The synthetic diet of HALVER et al.2) in which the levels of the test vitamins were varied respectively was used throughout the experi-ments (Tables 1 and 3). The general feeding technique was reported in the previous paper1) . The growth responses of the carp to dietary levels of riboflavin or pantotheni ?? acid and accumulation of these vitamins in hepatopancreas were employed as criteria for the nutritional adequacy. The requirements for riboflavin and calcium pantothenate of the carp thus determined by 6-week feeding trials were 0.23-0.33mg and 1.0 1.4 mg per kg of body weight per day respectively under the experimental conditions used (Tables 1 and 3 and Figs. 1 and 2). The symptoms of carp due to deficiency of these two vitamins are indicated in Table 2. The most prominent pathological findings observed were hemorrhage in various areas of the body in riboflavin deficiency and extremely poor weight gain in pantothenic acid deficiency.