The absorption, excretion and distribution of radioactive vitamin B_<12> in the body of albino rats were studied. In 24 hours after the oral administration of vitamin B_<12> labelled with Co^<60>, most of it was excreted in feces and only about 12 percent of it was absorbed in the body. The urinary excretion was, however, remarkedly increased by intracardiac injection. By any type of from the administration routes, great amount of the absorbed vitamin B_<12> was distributed in the kidney. Twenty four hours after an intramuscular injection of labelled vitamin B_<12> about 85 percent of it was retained in the body and even 10 days later, 60 percent was still remained. Five days after an oral administration of labelled vitamin B_<12>, the most of it was distributed in the intestinal walls, especially in the upper half of the small intestines. The absorption of vitamin B_<12> orally when given appeared to increase by adding human parotid saliva to it.