Abstract: The invention relates to 9-(phosphonylmethoxyalkyl)adenines of the general formula I ##STR1## wherein R.sup.1 is a hydrogen atom, and alkyl group containing one to three carbon atoms, or a hydroxymethyl group, R.sup.2 is a methylene, ethylene, propylene, ethylidene, methoxyethylene, benzyloxyethylene, tetrahydropyran-2-yloxyethylene, (1-ethoxyethoxy)ethylene or 1,2-O-isopropylidene-1,2-dihydroxypropylene group the method of their preparation and utilization.Compounds of the general formula I exhibit biological effects (e.g. antiviral) or can be converted into compounds with such effects.