Neurofibromatosis type 1 (von Recklinghausen' disease) is an autosomal dominant hereditary syndrome. It is characterized with multiple light brown (café-au-lait) spots, Lisch nodules and neurofibromas. Thorax and lungs are affected in various forms. Four cases with symptoms of thoracic involvement were investigated in our clinic. Mean age was 46. All cases had dyspnoea and cough; two of them had chest pain. Skin lesions of neurofibromatosis type 1 (NF 1) were pathologically confirmed in all cases. Moreover, case 3 had diffuse interstitial fibrosis and honeycomb pattern. Case 2 had thorax deformity, kyphoscoliosis and intrathoracic benign mass. Case 1 had two neurofibrosarcoma masses on the right hemithorax. Case 4 had multiple intrathoracic neurofibromas. Cases 1 and 3 died within two years after diagnosis due to malignancy and respiratory failure, respectively. Cases 2 and 4 are still under our control.