Abstract: Nucleotides of nucleosides or bases having known cytotoxic activity are reacted to form corresponding cytotoxic liponucleotide analogs by phosphorylation of molecular species of phosphatidic acids. The resulting cytotoxic liponucleotide analogs exhibit an enhanced therapeutic index and broader spectrum of antitumor activity as compared to the parent nucleoside or base compounds, apparently due to an improved selective uptake thereof by metabolizing tumor cells, and are thus useful cytotoxic, antiviral and antineoplastic agents.