The carbocyclic analogue of (E)-5-(2-bromovinyl)-2'-deoxyuridine, C-BVDU, is a very potent and selective anti-herpes-virus compound. In order to synthesize and study the properties of a DNA that contains C-BVDU, the 5'-triphosphate, C-BVDUTP was prepared and evaluated as a potential substrate of the E. coli Klenow DNA polymerase enzyme. Although C-BVDUTP proved to be a very poor substrate also of this enzyme, it could be incorporated up to 3.6% into the synthetic DNA, poly(dA-dT, C-BVDU). This level of substitution decreased significantly the template activity for DNA and RNA polymerases, as compared to that of poly(dA-dT).