Dirofilaria immitis, the dog heartworm, may accidentally infect humans and manifest as a subpleural solitary or multiple pulmonary nodules that are often difficult to differentiate from primary or metastatic lung tumors. Our patient had biopsy proven lung cancer and a second lesion found to be pulmonary dirofilariasis after excision. The coexistence of pulmonary infection and cancer must be considered whenever 2 or more lesions have different clinical and radiologic behavior. Pulmonary dirofilariasis is a rare cause of lung nodules and may be present with lung cancer even more infrequently.