A new class of acyclic adenosine analogues is described which exhibit broad-spectrum antiviral activity and are apparently targeted at S-adenosyl-L-homocysteine hydrolase. The compounds are all alkyl (i.e., methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, 2-methylpropyl, tert-butyl, 1-pentyl, 3-methylbutyl, 1-octyl, 2-hydroxyethyl, 2-methoxyethyl, furylmethyl, cyclohexyl) esters of (RS)-3-adenin-9-yl-2-hydroxypropanoic acid. They are inhibitory to a broad variety of viruses, including vesicular stomatitis, vaccinia, reo, parainfluenza, and measles, and, with one exception (the furylmethyl ester), nontoxic to the host cell at antivirally active concentrations. It is postulated that the alkyl esters are as such taken up by the cells and hydrolyzed within the cells to release the parent compound, 3-adenin-9-yl-2-hydroxypropanoic acid.