Abstract: Insulin-like growth factor 2 had a high expression in many cancers. In the current paper, the expression of Insulin-like growth factor 2 was investigated and its prognostic significance in lung adenocarcinoma with mediastinal lymph node metastasis was studied. Methods: A retrospective immunohistological analysis of specimens of lung adenocarcinoma with mediastinal lymphnode metastasis was conducted. All patients did not have neoadjuvant chemotherapy and/or radiotherapy. The prognostic factors of stage N2 lung adenocarcinoma and the impact of insulin-like growth factor 2 on the prognosis of patients with stage N2 lung adenocarcinoma were also studied. Results: Factors including T stage, station 7 metastasis, and the number of metastatic stations had an impact on the prognosis of stage N2 lung adenocarcinoma. The 5-year overall survival of patients with negative and positive expression of insulin-like growth factor 2 were 18% and 8%, respectively ( P = 0.034 ). Conclusion: The prognosis of stage N2 lung adenocarcinoma is poor. The prognostic factors of stage N2 lung adenocarcinoma include the T stage, station 7 metastasis, the number of metastatic stations, and the expression of insulin-like growth factor 2.