OBJECTIVES: To investigate the anti-fatigue effects of Myelophil, an extract of a mix of Astragali Radix and Salviae Radix, which has been used to treat patients with chronic fatigue. SUBJECTS AND DESIGN: A randomised, double-blind, controlled clinical trial was performed with 36 adults who complained of chronic fatigue. The subjects were divided among a control group and low- and high-dose groups (3 or 6g of oral Myelophil per day, respectively) and were monitored for 4 weeks. Fatigue severity was subjectively characterised, and the expression of 42 cytokines was evaluated using an antibody array. RESULTS: Myelophil administration (3g per day) significantly decreased the fatigue severity score compared with the control (p<0.05). No changes were noted in cytokine expression. CONCLUSIONS: Myelophil appears to have a pharmacological effect against fatigue, suggesting the clinical relevance of the traditional medicinal plants, Astragalus membranaceus and Salvia miltiorrhiza.