THOUGH the manner in which the four nucleotides of ribonucleic acid are combined in the intact molecule is not completely settled, the data obtained from analyses of the chemical degradation products are most compatible with phosphoryl-group attachments through the C2 and C3 positions of the ribose group1. The exclusion of C5 phosphoryl linkages rests principally upon the failure to isolate 5' nucleotides or the acid-stable ribose-5-phosphate from acid hydrolysates of ribonucleic acid. However, Gulland and Jackson2, hydrolysing yeast ribonucleic acid with a snake venom containing a phosphodiesterase and a specific 5' nucleotidase, found 35 per cent of the total phosphate liberated as inorganic phosphate, suggesting that a large number of the phosphoryl groups were attached to the ribose C5 position. Recently, Schmidt3, utilizing periodate titrations of ribonuclease-hydrolysed yeast ribonucleic acid, concluded that some nucleotide groups had been linked to positions other than ribose C2 or C3 in the original ribonucleic acid. The experiments described below indicate that intact 5' nucleotides can be isolated from enzymatically hydrolysed calf liver ribonucleic acid.