We have undertaken an active search for homeobox-containing sequences of Antp class (Hox genes) in the genome DNA of polychaete Nereis virens. This search was based on the high evolutionary conservation of these sequences, which made possible their amplification in the polymerase chain reaction with degenerate primers. As a result, eleven fragments of various Hox genes, including AbdB-like Nvi-post1, were cloned. Using pulsed-field electrophoresis, we have demonstrated that Hox genes corresponding to the isolated fragments are clustered in the genome of N. virens.