9-[2-(2-Hydroxyethoxy)ethoxymethyl] and related derivatives of certain 2-amino-6-substituted purines have been discovered to have potent anti-viral activities. Novel compounds and their pharmaceutically acceptable salts, pharmaceutical formulations containing the compounds of this invention, and the treatment of viral infection with these formulations are all disclosed. 9-[2-(2-hydroxyethoxy)ethoxymethyl] guanine and 2-amino-9-[2-(2-hydroxyethoxy)ethoxymethyl] adenine, i.e. 2,6-diamino-9-[2-(2-hydroxyethoxy)ethoxymethyl] purine, are examples of especially active compounds of this invention.