The inheritance of 65 RAPD markers obtained from 15 arbitrary primers has been tested in two sexual populations of the ostracod Heterocypris incongruens. The markers were selected using the criteria of reproducibility and banding-pattern clarity from the amplification products yielded by 40 primers. The expected inheritance model was inferred from the progeny banding pattern and tested with the appropriate statistics. All 65 markers followed a Mendelian pattern of inheritance and indicated that the Spanish and the Italian populations studied are genetically different.