Products of 1-methyladenosine, 2'-O-methyladenosine, 2'-O-methylcytidine, and 5-methylcytidine catabolism by resting cells of Staphylococcus aureus and Staphylococcus intermedius were chromatographically separated. The methyl group in 1-methyladenosine protected the adenosine derivative from deamination by S. intermedius but it did not protect N-glycosidic bond from cleavage by S. intermedius and S. aureus. The methyl group in 2'-O-methyladenosine and 2'-O-methylcytidine protected the N-glycosidic bond from cleavage by S. aureus and S. intermedius but it did not protect the adenosine and cytidine derivatives from deamination by S. intermedius. 5-Methylcytidine was converted by the common route in which 5-methylcytidine was first deaminated to ribothymidine which was cleaved to yield thymine. S. intermedius deaminated the purine and pyrimidine ribonucleosides adenosine, 2'-O-methyladenosine, cytidine, and 5-methylcytidine. Pyrimidine ribonucleosides (cytidine, 5-methyl-cytidine) were deaminated only slowly and purine ribonucleosides (adenosine, 2'-O-methyladenosine) not at all by S. aureus.