Pressed biscuits were fortified with gelatin encapsulated VA powder, VC phosphate Mg and VB2 tetrabutyrate. The biological effects of these vita-rains were examined by human experiments. In 7 days of the experimental period, the subjects of the 1st group (10 male adults) took the fortified biscuit freely which contained 7500 IU VA powder, 5.16 mg B2 tetrabutyrate ( = 3mg VB2) and 308mg VC phosphate ( = 140 mgVC) in 750 g. The 2nd group took 250 g biscuit freely containing the same amount of vitamin and unfortified pressed biscuit. The 3rd group took only the unfortified ones freely. 5 days before or after fhe experimental period the subjects ate vitamin restricted diets. The nutritional status of VB2 was estimated by 24 hrs. urinary VB2 values, that of VC by urinary and fasting plasma VC levels, and that of VA by fasting plasma VA values.The urinary levels of VB2, VC and plasma values of VC of group 1 and 2 at the end of the experimental period were significantly higher than those of the pre-experimental period. They were also higher than those of group 3. On the 5th day of the post-experimental period, the status of VB2 and VC of group 1 and 2 was still better than that of group 3. Because the subjects were not in VA deficiency, the plasma levels of VA were kept steady.The stabilities of these vitamins in the fortified pressed biscuit were compared with those of ordinary vitamins. Stored in 85% RH 32℃ for 20 months, encapsulated VA powder retained 76%, VC phosphate 84%, but the ordinary VA only 14%, VC 29%. Stored in room temp. 75% RH for 2 years, the VA encapsulated powder retained 73%, VC phosphate 96%, but ordinary VA only 8%, VC 22.3%. In room temp. for 2 years, encapsulated VA powder retained 87%, VC phosphate almost did not lost, but ordinary VA retained 8%, VC retained 25% only. The stability of the VB2 tetrabutyrate was almost the same as that of VB2. It was shown by the guinea pig growth experiment that VC phosphate in pressed biscuit stored 20 months possessed the same biological effect as VC crystal.