Background: Despite therapeutic advances, lung cancer remains the first cause of death from cancer. The main objective of this study was to identify risk factors associated with death within 3-months of the first hospitalization for lung cancer in France. Methods: This analysis included patients with a first hospitalization for lung cancer (between January 1, 2016 and December 31, 2018) according to diagnosis-related groups entered into the French national medical-administrative database. Clinical and socioeconomic parameters and characteristics of that first hospitalization were analyzed. A model predictive of early mortality was developed based on those variables. Results: The 144,087 included patients were 67% men; median age of 68 [interquartile range 60-76] years; 47% had metastatic disease at diagnosis; and 34% and 23%, respectively, had received systemic treatment or undergone curative surgery. The 3-month mortality was 19%, and significantly higher for those ≥70 versus <70 years old (OR 1.33, 1.22-1.45), men versus. women (OR 1.50, 1.44-1.55), those with metastatic disease at diagnosis (OR, 3.30, 3.18-3.43), first hospitalization via the emergency room (OR 1.65 1.59-1.71) and first hospitalization lasting >30 days (OR, 1.58 1.49-1.68). In contrast, no socioeconomic characteristic was associated with early mortality. Conclusion: Almost 1 in 5 patients diagnosed with lung cancer in France died within 3 months post-diagnosis. Improving survival requires diagnosis at an earlier stage and better organization of diagnosis and specific care pathways.