Objective: The aim of this study was to analyze the trend of incidence, clinicopathological characteristics and therapy of young (less than 40 years old) patients with advanced lung adenocarcinoma, and to identify the prognostic factors. Methods: The clinical data of 198 young patients with advanced lung adenocarcinoma were collected from the Cancer hospital and Institute of Chinese academy of Medical Sciences from January 2001 to June 2012. To analyze the trend of incidence, clinicopathological characteristics and therapy and evaluate the independent prognostic factors affecting survival time with Cox proportional hazards model. Results: From 2001 to 2012, the incidence of lung adenocarcinoma in young patients was increased year by year. Among the 198 patients, 92 were males and 106 were females. Their age was from 20 to 40 with a median age of 34 years. Most patients had poorly differentiated adenocarcinoma (46.7%) whereas 36.7% of the cases had moderately differentiated tumor. Among the 198 patients, there were 25 patients with stage ⅢB (12.6%) and 173 (87.4%) cases of stage Ⅳ cancer.The 1-, 3- and 5-year survival rates were 70.7%, 21.6% and 10.3%, respectively. Among the198 cases, patients who received epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) therapy, the median OS (25.6 months) was significantly longer than that of patients who never received EGFR-TKI therapy (13.3 months)(P<0.001). Since 2009, the number of cases detected for EGFR gene was gradually increased, and the median OS of patients diagnosed from 2010 to 2012 was 22 months, significantly higher than that of 16 months of patients diagnosed during 2001-2009 (P=0.019). The Cox regression analysis showed that the performance status, extra-pulmonary metastasis and whether received EGFR-TKI therapy were independent prognostic factors. Conclusions: The incidence rate of lung adenocarcinoma in young patients has an increasing trend. They have a high proportion of women and of poor differentiation. The patients can get benefits from EGFR-TKI therapy. Mutivariate Cox regression analysis shows that the performance status, extra-pulmonary metastasis and whether received EGFR-TKI therapy are independent prognostic factors for young patients with advanced lung adenocarcinoma.