Ixodes ricinus followed by Dermacentor reticulatus are the most common tick species with medical and veterinary importance in Poland. Ixodes ricinus is widely distributed across Poland, whereas the range of D. reticulatus is limited to the eastern and central parts of the country, with several new foci in the mid-west and west. Concurrently, an increase in the occurrence range of D. reticulatus has been observed. Recent studies indicate its high density in eastern Poland. The aim of the study was to determine the species composition of ticks infesting dogs from the northeastern part of Lublin Province. In a three-year study (2017-2019), 501 tick specimens were collected from 122 dogs in the north-eastern part of Lublin Province (eastern Poland). 174 ticks were removed from 24 pet dogs kept by individual owners and the other 327 were collected from 98 dogs from the animal shelter. Two tick species: D. reticulatus 55.5% (278/501) and I. ricinus 44.5% (223/501) were identified in the group of 501 ticks removed from the dogs. Dogs in the north-eastern part of Lublin Province are exposed to contact with two tick species: I. ricinus and D. reticulatus, with a higher frequency of the latter species. Identification of the species of ticks infesting dogs in an analyzed area and knowledge of pathogens transmitted by ticks facilitates correct differential diagnosis of tick-borne diseases.