Canine vector-borne diseases (CVBDs) have increasingly become a focus of attention in the past few years. Nevertheless, in many parts of Europe information on their occurrence is still scarce. In a large study in Poland 3,094 serum samples taken from dogs throughout all 16 Polish provinces were tested using a commercial kit for the detection of circulating antibodies against Anaplasma phagocytophilum, Borrelia burgdorferi sensu lato and Ehrlichia canis and of Dirofilaria immitis antigen. A total of 12.31 % (381/3,094; 95 % confidence interval [CI]: 11.18–13.52 %) and 3.75 % (116/3,094; 95 % CI: 3.11–4.48 %) of the dogs were positive for A. phagocytophilum and B. burgdorferi s.l. antibodies, respectively. Furthermore, 0.26 % (8/3,094; 95 % CI: 0.11–0.51 %) were positive for E. canis antibodies and 0.16 % (5/3,094; 95 % CI: 0.05–0.38 %) for D. immitis antigen. The highest percentages of A. phagocytophilum-positive dogs were noted in Lesser Poland, Silesia and Łódź Provinces. For B. burgdorferi s.l., the highest prevalence was recorded in Łódź Province. Co-infections with A. phagocytophilum and B. burgdorferi s.l. were recorded in 1.71 % of all examined dogs (53/3,094; 95 % CI: 1.29–2.23 %). One dog even had a triple infection, testing positive for E. canis too. Both A. phagocytophilum and B. burgdorferi s.l. have previously been reported in Poland and were confirmed in the present study by positive samples from all 16 provinces. Concerning E. canis and D. immitis travel history or importation cannot be excluded as factors which may have determined the occurrence of these pathogens in the relevant animals. Practitioners in Poland should be aware of the above mentioned CVBDs and of prophylactic measures to protect dogs and their owners.