The significance of the presence of N2 disease in patients with non-small cell cancer of the lung is widely misunderstood. Long-term survival rates from 15% to more than 30% after surgical resection are frequently reported in the literature. However, these percentages represent only the surgical results in a highly selected and unfortunately small proportion of the entire number of patients with N2 disease. In those patients in whom N2 disease is readily clinically recognizable or is identified by standard roentgenographic or bronchoscopic study and proved by biopsy or is discovered by prethoracotomy mediastinal exploration, a 5-year survival rate of only approximately 2% for the entire group can be expected, even when aggressive surgical resection is performed when appropriate. In those patients in whom the N2 disease is only initially recognized at thoracotomy, the resectability rate is higher and 5-year survival rates as noted are in the range of 15% to 30%. Although surgical resection continues to be the primary choice of therapy in this small group (less than 20% of patients with N2 disease), surgical resection can be expected to salvage only 3% to 6% of all patients with N2 disease. Thus, with presently available therapy, the vast majority of patients proved to have N2 disease will die of their lung cancer. It must be concluded that N2 disease is a significant poor prognostic factor in patients with lung cancer.