There is limited information about survival of Stage I lung cancer diagnosed by screening.What was the survival rate of screen-detected Stage I lung cancer in the National Lung Screening Trial (NLST), and was it affected by screening method, patient or tumor characteristics, or treatment method?The study cohort consisted of all NLST participants with screen-detected Stage I lung cancer. Lung cancer-specific survival for Stage I overall and for IA and IB substages were compared in the low dose CT (CT) and chest radiography (CXR) screening randomization arms, and with an analogous cohort from the Surveillance, Epidemiology, and End Results Program (SEER) of the National Cancer Institute, using the cumulative incidence competing risk method. Cox proportional hazards models were used to evaluate the association between lung cancer-specific survival and screening arm, patient factors, primary tumor size, and treatment.There were 324 screen-detected Stage I lung cancers in the CT arm and 125 in the CXR arm. The 10-year survival in the CT arm was greater than in the CXR arm (73.4% vs. 64.6%, p=0.05), and both were greater than in SEER (55.6%, p<0.001 vs. CT arm, p=0.04 vs CXR arm). Proportional hazards models revealed greater likelihood of survival in the CT arm (HR 0.69, 95% CI 0.5-0.98), and with primary tumor size below the median of 17 mm (HR 0.61, 95% CI 0.42-0.88). There was no survival difference between treatment with limited resection vs. full resection (HR 1.12, 95% CI 0.65-1.9), while nonsurgical treatment was associated with reduced likelihood of survival compared to full resection (HR 3.0, 95% CI 1.5-5.9).Long-term lung cancer-specific survival of Stage I lung cancer was greater with CT than with CXR screening or in the general population, for smaller primary tumor size, and with surgical treatment.