Objectives: To study the effect of fetal stem cell(FSC) therapy on Grade Ⅰ and Ⅱrespiratory failure in patients with amyotrophic lateral sclerosis(ALS) and muscular dystrophy(MD). Methods: A comparative study was conducted on 41 patients with Grade Ⅰ or Ⅱrespiratory failure(RF) resulting from ALS or MD. The patients were divided into 4 groups according to the underlying disease and the degree of RF. Patients underwent combined treatment, including the experimental application of FSC therapy, and were examined before FSC treatment, and 6 months and 12 months after treatment. Results: FSC treatment improved both subjective and objective breathing parameters as early as 6 months post‐treatment. A significant increase in the forced vital capacity(FVC) and forced expiratory volume in 1 second(FEV1) was reported by all patients with grade Ⅰ RF linked to ALS and MD compared to baseline. Patient respiratory improvement was maintained over the next 6 months. Grade Ⅱ RF patients with MD reported a significant improvement in FVC 12 months after treatment. Conclusions: Evidence for respiratory improvement was observed as early as 6 months in all patients after combined treatment including FSC therapy, and this was maintained for a further 6 months after therapy. In MD patients with Grade Ⅱ RF, treatment resulted in a significant FVC and FEV1 increase within 6 months and downgrading to Grade Ⅰ RF within a year after FSC treatment. Objectives: To study the effect of fetal stem cell (FSC) therapy on Grade I and II respiratory damage in patients with amyotrophic lateral sclerosis (ALS) and muscular dystrophy (MD). Methods: A comparative study was conducted on 41 patients with Grade I or The patients were divided into 4 groups according to the underlying disease and the degree of RF. Patients underwent combined treatment, including the experimental application of FSC therapy, and were examined FSC treatment, and 6 months and 12 months after treatment. Results: FSC treatment improved both subjective and objective breathing parameters as early as 6 months post-treatment. A significant increase in the forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) was reported by all patients with grade Ⅰ RF linked to ALS and MD compared to baseline. Patient respiratory improvement was maintained over the next 6 months. Grade Ⅱ RF patients wi th MD reported a significant improvement in FVC 12 months after treatment. Conclusions: Evidence for respiratory improvement was observed as early as 6 months in all patients after combined treatment including FSC therapy, and this was maintained for a further 6 months after therapy. In MD patients with Grade II RF, treatment resulted in a significant FVC and FEV1 increase within 6 months and downgrading to Grade I RF within a year after FSC treatment.