Synthetic oligodeoxynucleotide probes, 21-23 nucleotides in length, were prepared which specifically hybridize to the genomes of the wild type 1 and 3 polioviruses currently endemic to the northeastern region of Brazil. The probes are complementary to sequences near the 5'-terminus of the VP1 gene that differ substantially among genetically distant polioviruses but are largely conserved among related isolates. The probes have been routinely used in the laboratory surveillance of poliomyelitis cases in Brazil, permitting direct, rapid identification of the indigenous wild polioviruses by dot-blot hybridization.