Wheat dwarf virus (WDV) has been one of the most common viruses on cereal crops in Poland in the last years. This single stranded DNA virus is transmitted by the leafhopper spec, Psammotettix alienus (Dahlb.) in a persistent manner. It induces yellowing and streaking of leaves, dwarfing or even death of infected plants. The presence of barley- and wheat-specific forms of WDV (WDV-B and WDV-W) and their vector were previously reported in the country, however the literature data did not include any information on the infectivity of the vector in Poland. A duplex polymerase chain reaction (PCR) procedure was developed and optimized for simultaneous detection and differentiation of both forms in the vector. Two sets of primers amplify 734 bp and 483 bp specific fragments for WDV-W and WDV-B, respectively. The results were verified by a sequencing method. The studies were carried out on insect samples collected in autumn from four different locations in Greater Poland. The results confirmed the presence of WDV-W in the tested samples. They also suggested the concomitant of both forms of the virus in the vector. Additional studies to determine virus-vector relationships should be undertaken.