Objective:To investigate the expression of heat shock protein 90 (HSP90) and the relationship between the expression of HSP90 and the clinicopathological features or prognosis in patients with lung adenocarcinoma (ADC).Methods:The paraffin specimens of 193 patients with lung adenocarcinoma and 53 non cancerous lung tissues (bullae and bronchiectasis) resected in Xiangya Second Hospital of Central South University were analyzed retrospectively. The expression of HSP90 in the tissue chip was detected by immunohistochemical streptavidin-perosidase (SP) method by high-throughput tissue chip, and the relationship between its expression level and the clinicopathological characteristics of patients was analyzed; Kaplan Meier survival curve was used to analyze the difference between different expression levels of HSP90 and the overall survival time of patients with lung adenocarcinoma.Results:The positive expression of HSP90 in lung adenocarcinoma was significantly higher than that in non cancerous lung tissue ( P<0.001), the expression level of HSP90 in clinical stage Ⅲ patients was higher than that in clinical stage Ⅰ-Ⅱ patients ( P=0.008), and the expression level of HSP90 in patients with lymph node metastasis was higher than that in patients without lymph node metastasis ( P=0.024); The 10-year survival rate of lung adenocarcinoma patients with high expression of HSP90 was significantly lower than that of patients with low expression of HSP90 ( P=0.001). The 10-year survival rate of lung ADC patients with stage Ⅲ and lymph node metastasis was significantly lower than that of patients with stage Ⅰ-Ⅱ and no lymph node metastasis ( P<0.05). Multiple Cox proportional hazard regression analysis further identified that lung ADC patients with overexpression of HSP90 had a poor prognosis ( P=0.010). Conclusions:HSP90 might play an important part in the development and progression of lung ADC and might act as a novel prognostic marker for patients with lung ADC.