The distribution of (1-14C) pantothenic acid was studied in two different experiments with rats. Single dose kinetics were carried out over a period of 168 hours. In this experiment it could be shown that besides the urinary and faecal output a third route of excretion exists: the respiratory pathway. The tissues with the highest retention capacity were the kidneys, pituitary gland, heart, muscle, liver and the adrenal glands. In a second experiment - performed as steady state study, lasting 35 days - during the investigated period and finally in the steady state the above mentioned tissues showed the highest affinity for pantothenic acid, indicating an intensive metabolism of this vitamin. These results are discussed, especially towards pantothenic acid and acetyl coenzyme A-depending functions.