Chronic obstructive pulmonary disease (COPD) refers to a group of widely diffuse diseases that cause airflow blockage characterized by persistent respiratory symptoms such as dyspnea, chronic cough, recurrent wheezing, chronic sputum production, and progressive restricted airflow associated with exacerbations. COPD is the third leading cause of death worldwide and can only be treated not cured. Pulmonary function tests do not permit the identification of initial obstructive airways disease. Forced expiratory flow (FEF25-75), which calculates obstruction severity at small and medium bronchial airways levels, allows an early COPD diagnosis. We report a 72-year-old ex-smoker male not exposed to occupational risk with symptoms suggesting early COPD. Baseline pulmonary function tests were normal, except FEF25-75. The patient did not respond to the first 6 months of treatment with long-acting muscarinic antagonist (LAMA), whereas he showed a clear clinical and FEF25-75 response to 1-year treatment with LAMA associated with long-acting β2 agonist (LABA). This clinical case report highlights the usefulness of FEF25-75 evaluation in early COPD diagnosis and monitoring and confirms the efficacy of LAMA-LABA association for small airways obstruction treatment.