This work presents the finding of Dirofilaria repens microfilariae after necropsy on a dog in Croatia. The cause of death was peritonitis caused by perforation of the intestinal diverticula. Necropsy revealed severe cachexia with a phlegmonous subcutaneous inflammation in the cubital, coxal and carpal regions. The liver cirrhosis with icterus was also seen. Histopathological examination showed numerous microfilariae in all examined organs located predominantly intravascularly, but in the phlegmone, liver, lymph node and lungs they were located in the tissue of the haemorrhage area. Two otherwise healthy dogs which had lived in cohabitation with the necropsied one had been found positive by modified Knott's test for D. repens microfilariae and were successfully treated with ivermectin. Key words: Dirofilaria repens, dog, pathomorphology U radu je prikazan nalaz invazije psa parazitom Dirofilaria repens koja je utvrdena razudbom. Uzrok smrti bio je peritonitis uzrokovan rupturom crijevnog divertikula. Razudbom je utvrdena teska kaheksija, flegmonozna upala potkozja u lakatnom, koksalnom i karpalnom podrucju to jetrena cirozapracena zuticom. Histopatoloskom pretragom uocene so mnoge mikrofilarije u svim pregledanim organima, pretezito intravaskulamo, u flegmoni, jetri, limfnom cvom i plucima. U druga dva, inace zdrava psa, koji so drzani zajedno s razudenom zivotinjom, utvrdena je dirofilarioza Knottovim testom, koja je bila izlijecena ivermektinom. Kljucne rijeci: Dirofilaria repens, pas, patomorfologija