Phosphate triester derivatives of the anti-neoplastic alkyl lysophospholipids (ALP) have been prepared as novel potential therapeutic agents. In particular, simple, symmetrical phosphate triesters have been prepared, using phosphorochloridate chemistry. The compounds have been fully characterized by a range of techniques, and assayed for their inhibition of DNA synthesis by mammalian cells in culture. The compounds are generally inhibitory towards DNA synthesis in the micromolar range. However, the magnitude of the effect varies greatly with the phosphate structure. In particular, there is a clear trend towards decreasing activity with increasing alkyl chain length. Thus, short-chain dialkyl phosphate esters appear more effective than the reference compound hexadecyl phosphatidyl choline.