Non-small cell lung cancer (NSCLC) patients presenting with miliary intrapulmonary carcinomatosis (MIPC) have been reported that had higher rate of epidermal growth factor receptor (EGFR) mutation and rapidly fatal courses. We investigated the clinical characteristics and prognostic value of stage IV NSCLC patients with MIPC at initial diagnosis in Korean NSCLC patients. Our study included 241 patients who had newly diagnosed stage IV lung adenocarcinoma between 2007 and 2012. We reviewed clinical data and EGFR mutation status. MIPC defined as multiple nodules (≤3 cm in greatest dimension) diffusely distributed throughout both lung fields. Of 241 patients, 22 patients (9.1%) had MIPC at initial diagnosis. Compared with 219 patient (90.9%) without MIPC, who presenting MIPC were younger (61.6±10.9 vs. 64.7±14.1, p=0.039), revealed higher proportion of never smoker (77.8% vs. 46.2%, p=0.037), had higher EGFR mutation rate (61.9% vs. 42.5%, p=0.087), and had more distant metastasis, especially bone and kidney. Among patient with MIPC, EGFR-TKI (tyrosine kinase inhibitor) group had longer median progression free survival (PFS) than chemotherapy group as first-line therapy (6.97 vs. 2.13 months, p=0.001). Of 107 patient with EGFR mutation, who presenting MIPC (n=13, 12.1%) showed shorter progression free survival during EGFR-TKI therapy(6.97 vs. 9.87 months, p=0.048). Conclusions: In Korean Stage IV lung adenocarcinoma patients with MIPC showed higher EGFR mutation rates as is known, but EGFR mutant patients presenting MIPC had relatively lower benefit from EGFR-TKI therapy. Non-small cell lung cancer (NSCLC) patients presenting with miliary intrapulmonary carcinomatosis (MIPC) have been reported that had higher rate of epidermal growth factor receptor (EGFR) mutation and rapidly fatal courses. We investigated the clinical characteristics and prognostic value of stage IV NSCLC patients with MIPC at initial diagnosis in Korean NSCLC patients. Our study included 241 patients who had newly diagnosed stage IV lung adenocarcinoma between 2007 and 2012. We reviewed clinical data and EGFR mutation status. MIPC defined as multiple nodules (≤3 cm in greatest dimension) diffusely distributed throughout both lung fields. Of 241 patients, 22 patients (9.1%) had MIPC at initial diagnosis. Compared with 219 patient (90.9%) without MIPC, who presenting MIPC were younger (61.6±10.9 vs. 64.7±14.1, p=0.039), revealed higher proportion of never smoker (77.8% vs. 46.2%, p=0.037), had higher EGFR mutation rate (61.9% vs. 42.5%, p=0.087), and had more distant metastasis, especially bone and kidney. Among patient with MIPC, EGFR-TKI (tyrosine kinase inhibitor) group had longer median progression free survival (PFS) than chemotherapy group as first-line therapy (6.97 vs. 2.13 months, p=0.001). Of 107 patient with EGFR mutation, who presenting MIPC (n=13, 12.1%) showed shorter progression free survival during EGFR-TKI therapy(6.97 vs. 9.87 months, p=0.048). Conclusions: In Korean Stage IV lung adenocarcinoma patients with MIPC showed higher EGFR mutation rates as is known, but EGFR mutant patients presenting MIPC had relatively lower benefit from EGFR-TKI therapy.