Blood samples of pigs were analyzed for vits. A, C, and niacin before nursing, during the suckling period, and after weaning. At birth the plasma vit. C and blood niacin were relatively high (0.96 mg. % and 8 microg./cc, respectively) and the plasma vit. A was low (0.1 microg./cc.). The vit. C level increased approx. 1.5-fold at 36 hrs. of age and decreased to 0.8 mg. % by the 2d week; after weaning the vit. C level was lower. The plasma vit. A reached a max. of 0.34 microg. in the week old pig, decreased during the middle of the suckling period, and rose again during the latter part. A lower level of vit. A was noted after weaning. The niacin level decreased to 5 microg. after weaning. Parturition did not affect the concn. of vits. A and C in sow''s blood. Carotene could not be detected in swine blood.