Phosphoramidate derivatives of 5-fluoro-2-deoxyuridine are disclosed for use in the treatment of cancer, especially in the treatment of cancer where the patient shows resistance, for example, in a patient with cells with a lowered level of nucleoside transporter proteins and/or with nucleoside kinase-deficient cells and/or with mycoplasma-infected cells and/or with cells with a raised level of thymidylate synthase.
