The aim of this study is to reveale the prevalence of dirofilarial infections in pet dogs. From the year 2010 to the year 2012, a total of 77 blood samples were collected from privately owned pet dogs in Novi Sad. All samples were examined by wet blood smears, the modified Knott test and heartworm antigen test. Circulating microfilariae of both Dirofilaria (D.) immitis and D. repens were found in dogs. Prevalence values for D. immitis and D. repens were 9,09% and 12,99%, respectively. Results of this study, compared with results of previous investigations, shows increase of infection with D. immitis and decrease of infection with D. repens. Further investigations are required with higher number of samples to confirm this findings.