Background: Thoracic radiation (RT) is associated with respiratory toxicities, which may reduce patients’ physical performance and their overall quality of life (QOL). Yoga therapy may buffer against disease and treatment-related sequelae. The purpose of this RCT is to establish feasibility and preliminary efficacy of a yoga intervention. Because family caregivers also report symptom burden (e.g., distress, sleep disturbances) we included them as active participants in this trial. Methods: Non-small cell lung cancer patients undergoing RT and their caregivers were randomized to a 15-session yoga or a waitlist control (WLC) group. Prior to RT initiation and randomization, both groups completed measures of QOL (SF-36 domains). Patients also completed the 6-minute walk test (6MWT) to measure physical performance. Dyads were reassessed at the last day of RT and then 3 months later. Results: We approached 47 eligible dyads of which 32 (68%) consented and 26 (81%) completed all assessments. Patients (mean age: 73 yrs., 63% female, 67% stage III) and caregivers (mean age: 62 yrs., 38% female, 63% spouses) completed a mean of 12 sessions, and 96% of them rated the program as “very useful”. Controlling for baseline levels and other relevant covariates, multilevel modeling revealed a clinically and statistically significant difference in patients’ 6MWT (yoga mean = 478m vs. WLC mean = 402m, d= 1.19; p < .05) and clinically significant differences in the physical function, role performance and mental health domains of the SF-36. For caregivers, clinically significant improvements were found in vitality and role performance. Conclusions: Yoga therapy appears to be a feasible and beneficial supportive care strategy for lung cancer patients and caregivers. A larger efficacy trial with a more stringent control group is warranted. Clinical trial information: NCT02196844