Background: Although asthma is typically characterized as a childhood disease, it can develop later in life. Older asthmatic patients may be at increased risk for corticosteroid adverse effects. We developed a novel traditional Chinese medicine to treat asthma called antiasthma simplified herbal medicine intervention (ASHMI). Herbal products may offer safer adjunctive treatment for older asthmatic patients. Objective: To investigate the effects of ASHMI on characteristics of allergic asthma in an aged mouse model of asthma. Methods: BALB/c mice (6 weeks old [young] and 6, 12, and 18 months old [aged]) received ASHMI treatment before and during intraperitoneal ovalbumin sensitization and intratracheal challenges. The control groups were untreated, age-matched, ovalbumin-sensitized and ovalbumin-challenged mice (ovalbumin mice) and naive mice. After the final antigen challenge, airway pressure (defined as the time-integrated change in peak airway pressure) after acetylcholine provocation was measured, representing airway hyperresponsiveness, and bronchoalveolar lavage fluid, sera, lung tissues for histologic analysis, messenger RNA, and collagen were collected. Results: Mean time-integrated change in peak airway pressure values in 6-week-old and 6-, 12-, and 18-month-old ASHMI ovalbumin mice were significantly reduced compared with those of age-matched, nontreated ovalbumin mice. Bronchoalveolar lavage fluid eosinophil numbers were significantly lower in all ASHMI ovalbumin mice. Treatment with ASHMI of young and aged ovalbumin mice resulted in significantly decreased lung inflammation, detected via hematoxylin-eosin staining; airway mucous cell metaplasia, determined by means of periodic acid-Schiff staining; and messenger RNA copy numbers of the mucin gene MUC5AC. Levels of ovalbumin specific IgE and the TH2 cytokines interleukin 4 (IL-4), IL-5, and IL-13 in lung and splenocyte cultures were reduced. Interferon gamma secretion was increased. Treatment with ASHMI reduced collagen production. Conclusion: Treatment with ASHMI reduces several features of asthma in aged antigen-sensitized and antigen-challenged mice.