Cytosine arabinoside (ara-C) and gemcitabine (dFdC) are two standard chemotherapy drugs used in the treatment of patients with various cancers. To alter the pharmacokinetic and pharmacodynamic properties of these molecules, we conjugated a synthetic phospholipid to both ara-C and dFdC and investigated their chemotherapeutic potential. The dFdC conjugate had greater cytotoxic activity compared with the ara-C conjugate and demonstrated notable cytotoxicity against all human cell lines tested.