In 2006 and 2007, a total of 193 blood samples were collected from privately owned dogs housed predominantly outdoors, resident in four provinces in Vojvodina, Serbian Republic. Circulating microfilariae of Dirofilaria repens, Dirofilaria immitis and Acanthocheilonema reconditum were found in 49.2%, 7.2% and 2.1% of dogs, respectively. Two additional occult heartworm infections were revealed with an antigen test of 90 amicrofilaraemic dogs. Prevalence values were not influenced by sex and breed, but D. repens was significantly more prevalent in dogs > or =6 years old, and differences were observed between provinces. This is the first detailed survey on canine dirofilariasis in the continental part of the Balkans. Vojvodina is shown to have the northernmost limit of heartworm infection in the Balkan area and one of the zones in Europe with the highest prevalence of canine subcutaneous dirofilariasis. Chemoprophylaxis should be considered for resident dogs and dogs visiting this region.