Objectives: This study was to evaluate the effectiveness and safety of Bojungikgi-tang for lung cancer patients with anorexia.Methods: This was a single-arm, open-label, and single-center trial, and suitable participants took Bojungikgi-tang (Buzhongyiqi-tang in Chinese, Hochuekki-to in Japanese) three times a day before or between meals for six weeks (42 days). After registration of clinical trials (visit 2), they visited the hospital every three weeks (visits 3 and 4) and measured or tested the effectiveness or safety evaluation variables to analyze the results. The primary outcome was the anorexia/cachexia subscale (A/CS) of functional assessment of anorexia/cachexia therapy (FAACT) score.Results: Seventeen lung cancer patients were included in the intention-to-treat (ITT) analysis. Lung cancer patients had higher A/CS of FAACT scores after six weeks of Bojungikgi-tang administration compared to that at the baseline. This was not significant four lung cancer (p=0.1668). In the secondary outcomes, the visual analog scale (VAS) score of anorexia decreased significantly (p=0.0009), and the CD4/CD8 ratio (p=0.0396) and CD4 levels (p=0.0345) significantly increased after six weeks of treatment. No serious adverse events were reported with Bojungikgi-tang in lung cancer patients.Conclusions: Bojungikgi-tang can be an effective and safe treatment for anorexia in lung cancer patients undergoing chemotherapy.