Solitary pulmonary nodule caused by Dirofilariasis immitis (dog heartworm), a filarial nematode, is a rare lung parasitic infection. Man is a ”dead end” host of D. immitis. The greatest problem that D. immitis creates in the human body is focal pulmonary infarction with a secondary granulomatous and fibrotic reaction after necrosis of the worm. We reported a 53-year-old male patient with a solitary pulmonary nodule in the left upper lung caused by dirofilariasis. The solitary nodule caused by human pulmonary dirofilariasis is easily confused with cancer. Clinicians should be alert to the possibility of pulmonary dirofilariasis when a solitary, noncalcified pulmonary nodule is noted.