Primary malignant melanoma of the lung (PMML) is a rare neoplasm that may be misdiagnosed as one of the more common types of lung cancer. Most cases are characterized by a very poor prognosis, ultimately leading to the patient's death. Since an optimal systemic treatment schedule is not established so far, early detection of lymph node metastases may be important for surgical interventions. We report on a 55-year-old male patient with a primary bronchial malignant melanoma of his left lower lobe that was treated by pneumonectomy. 11 and 17 months after removal of the PMML, suspicious lymph nodes in the patient's left axilla were identified by 7.5 MHz-ultrasound examinations. Again surgical treatment was performed and histopathology showed lymph node metastases of malignant melanoma. During adjuvant therapy with interferon alpha (3 x 6 Mio IE per week) no further relapse has been observed with a follow-up of 8 months after the last operation. An overview of primary melanoma of the lung is given and diagnostic options are discussed. The 7.5 MHz-ultrasound examination appears to be especially helpful in the early detection of lymph node metastases leading to early initiation of surgical treatment possibly associated with a prolonged survival in our patient.