Hochuekkito, a traditional herbal medicine, is occasionally prescribed in Japan to treat patients with a poor general condition. We aimed to examine whether this medicine was beneficial and tolerable for patients with progressed pulmonary Mycobacterium avium complex (MAC) disease.This pilot open-label quasi-randomized controlled trial enrolled 18 patients with progressed pulmonary MAC disease who had initiated antimycobacterial treatment over one year ago but were persistently culture-positive or intolerant. All patients continued their baseline treatment regimens with (n = 9) or without (n = 9) oral Hochuekkito for 24 weeks.Baseline characteristics were generally similar between the groups. Most patients were elderly (median age 70 years), female, had a low body mass index (<20 kg/m2), and a long-term disease duration (median approximately 8 years). After the 24-week treatment period, no patient achieved sputum conversion. Although the number of colonies in sputum tended to increase in the control group, it generally remained stable in the Hochuekkito group. Radiological disease control was frequently observed in the Hochuekkito group than the control group (8/9 vs. 3/9; p = 0.05). Patients in the Hochuekkito group tended to experience increase in body weight and serum albumin level compared with those in the control group (median body weight change: +0.4 kg vs. -0.8 kg; median albumin change: +0.2 g/dl vs. ±0.0 g/dl). No severe adverse events occurred.Hochuekkito could be an effective, feasible adjunct to conventional therapy for patients with progressed pulmonary MAC disease. Future study is needed to explore this possibility.UMIN Clinical Trials Registry UMIN000009920.