In 2011-2013 1588 samples of dogs' blood were examined for dirofilariosis using Knott method, as well as the Kingston and Morton method. The species of microfilariae was determined on the basis of morphometric characteristics. Samples were also examined using the Canine Heartworm Antigen Test. Positive samples were examined using a multiplex PCR assay for species confirmation. Microfilariae belonging to the species D. repens were found in the blood samples of dogs from all the provinces of Poland. The mean prevalence of this species observed in Poland was 11.7%. The range of intensity of infection was counted using the number of microfilariae found in 60 microl of blood amounted to between 1 and 158, and the mean intensity was 18 microfilariae. Microfilariae and antigens of D. immitis were not found in any examined blood samples.