The spread of canine and human dirofilariasis was first studied in the Moscow Region, a low disease transmission risk area. D.repens infestation was found to have a tendency to increase in Moscow residents with the imported cases being predominant. In 33 (84.6%) districts of the Moscow Region, dogs were registered to have D. immitis and D. repens infestation, with the former being preponderant in 31 districts. An original map of dirofilariasis distribution was compiled with the areas being singled out at a distance of Moscow: 15-20 km (6 districts) (the first ring); as long as 70 km (11 districts) (the second ring), and over 70 km (16 districts) where infestation rates greatly varied in both the number of infected animals and human beings and the species of causative agents.