A series of N 1-(phosphonoalkyl)uracils was prepared in a two-step reaction sequence from ω-aminoalkylphosphonates and (E)-3-ethoxyacryloyl isocyanate followed by the uracil ring closure. Under standard conditions (NCS; NBS; I2/CAN) all N 1-(phosphonoalkyl)uracils were transformed into the respective 5-halogeno derivatives to be later benzoylated at N3. All compounds were evaluated in vitro for activity against a broad variety of DNA and RNA viruses. One compound was slightly active against human cytomegalovirus in HEL cell cultures (EC50 = 45 μM) while another showed weak activity against varicella-zoster virus (TK+ VZV strain OKA and TK- VZV strain 07-1) with EC50 = 43 and 53 µM, respectively. In addition, several compounds exhibited noticeable inhibitory effects on the proliferation of human cervical carcinoma cells (HeLa) at a concentration lower than 200 μM.