To characterize the natural history of patients with a single brain metastasis at initial diagnosis of non-small cell lung cancer (NSCLC) and treated with radiosurgery (SRS) alone. An IRB-approved institutional registry of SRS cases treated from 1/1997-7/2012 was queried for patients with newly diagnosed NSCLC treated with SRS for a single brain metastasis. Patients receiving adjuvant whole brain radiation therapy were excluded. Extracranial lung cancer stage, symptomatic disease, Karnofsky performance status(KPS), timing and sites of first progression, SRS treatment parameters and use of local thoracic therapy (surgery or radiation therapy) were included in the analysis. Survival was analyzed by Kaplan-Meier analysis and log-rank tests, with multivariable modeling using proportional hazards. Of 2100 lung cancer cases receiving SRS, 52 met criteria for this analysis. Median age was 64 years, median KPS was 90, and histology was adenocarcinoma (38.5%), squamous (23%) and other (38.5%). 76% of pts received chemotherapy and 42% of patients received thoracic therapy (12% XRT, 32% surgery). Median brain metastasis size was 1.55 cm and median SRS dose was 24 Gy (range, 15-24 Gy). Median overall survival (OS), progression free survival (PFS) and CNS progression free survivals (CNS-PFS) were 13.7, 4.6 and 6.1 months, respectively. Twenty-five (48%) of patients experienced in brain failure (76% in brain, 12% SRS local failure, 12% both) and in 18 (35%) brain failure was the first site of failure. 52% of patients were salvaged by SRS as the first modality. Actuarial rates of CNS failure among surviving patients at 6, 12 and 18 months after SRS were 45, 55 and 71%, respectively. Outside of the brain, patients with asymptomatic chest-only or asymptomatic systemic disease at the time of radiosurgery had median OS of 20.2 and 14.1 months, respectively. Among patients with progressive/symptomatic thoracic or systemic disease, OS was significantly inferior: median 4.6 and 1.4 months, respectively (p < 0.0001). Improved median OS was seen with high KPS (90-100) OS 21.7 vs 3.0 months (p = 0.0008), and chemotherapy treatment 20.5 vs 5.7 months (p = 0.0168) but neither was significant in a multivariable model. Patients with a single brain metastasis from NSCLC at first presentation can have prolonged survival but brain failure after SRS alone is common and often the site of first failure. Patients with a single brain metastasis and symptomatic extracranial NSCLC at diagnosis have very poor survival after SRS, suggesting minimal benefit from this modality in this setting.