Limited information is available about the overlapping diagnoses of asthma and chronic obstructive pulmonary disease (COPD), sometimes known as overlap syndrome, in older people with asthma. In 52 outpatients with physician-diagnosed asthma, aged 75 years and older, we performed chest high-resolution computerized tomography and assessed the presence of pulmonary emphysema (low-attenuation area). For the pulmonary function test, we measured pre- and postbronchodilator forced expiratory volume (FEV₁), peak expiratory flow (PEF), and carbon monoxide diffusing capacity of the lung (DL_CO). The efficacy of adding tiotropium bromide to the treatment was also examined. Of 52 patients, 29 had emphysema; the frequency was higher in men than in women (71% vs. 28%). The values for FEV₁ were not different between patients with or without COPD, but COPD (+) patients with moderate and severe asthma had significantly lower DL_CO and reversibility of FEV₁ compared with COPD (-) patients. The duration of asthma was not related to FEV₁ or PEF, but inversely correlated with postbronchodilator FEV₁ (p=0.029) and with reversibility of FEV₁ (p=0.037). Treatment with tiotropium bromide for 8 weeks increased FEV₁ by 136±29 ml. In conclusion, in our patient group, aging and asthma duration resulted in “fixed” or irreversible airflow obstruction, and the addition of an anticholinergic agent to the treatment should be considered.