A survey of canine heartworm infections among 83 dogs (Male 42, Female 41) of pet dogs in Ulsan area was performed from March to July 2009 using antigen test. Of 83 dogs, 6 dogs (7.2%) were infected with the Dirofilaria immitis, and 5 dogs (6%) were detected to have microfilaria in the peripheral blood. The infection according to the age of 4~5, 6~7, 7 over years were 7.4%, 12.5%, and 10.5%, Also, A survey of canine heartworm infections among 23 dogs (Male 15, Female 8) of hunting dogs in Ulsan area was performed from July 2008 using antigen test. Of 23 dogs, 11 dogs (47.8%) were infected with the D. immitis, and 6 dogs (26.1%) were detected to have microfilaria in the peripheral blood. The infection according to the age of under 1, 2-3, 4-5, 6-7 over years were 12.5%, 40%, 85.7% and 66.7%, respectively.