The random amplified polymorphic DNA (RAPD) method was applied to eight Gobio gobio populations living in the rivers of the Czech Republic and Slovakia. The application of seven RAPD primers yielded eight fingerprint characteristics for the populations examined. Forty diagnostic markers have been identified, which can reliably identify the populations under study. Intrapopulation diversity varied between 0.26 and 0.38. A phenogram documented the close agreement of the particular populations with the geographic pertinence of their localities to the different sea basins.