The synthesis of two new nucleotide analogues is described. 5'-Sulfamino-5'-deoxyadenosine (1) was prepared by reaction of 5'-amino-5'-deoxyadenosine with (CH3)3N.203, and 5'-sulfamino-5'-deoxythymidine (2) was prepared from 5'-amino-5'-deoxythymidine by a similar reaction. The 5'-sulfamino nucleosides are shown to be quite stable to hydrolysis in acidic or basic aqueous solution Tests show that these compounds do not inhibit the growth of Escherichia coli or L1210 cells at concentrations less than 10(-4) M. At 10(-4) M compound 2 was found to give 70% inhibition of the replication of herpes simplex virus (type 1) with no effect on host cell growth (CV-1 monkey line).