[Purpose] The aim of this study was to analyze and compare respiratory function and activities of daily living (ADL) of spinal cord injury (SCI) and stroke patients and normal elderly people, as well as to examine the relationship between respiration and ADL in these groups. [Subjects and Methods] This study’s subjects were patients with spinal cord injury (n=30) and stroke (n=31), one year or longer after onset of their conditions, and a control group of ordinary elderly people (n=30). Measurements were made of their vital capacity (VC), forced vital capacity (FVC), forced expiratory flow (FEF), forced expiratory volume at one second (FEV1), FEV1/FVC, peak cough flow (PCF), and activities of daily living (ADL). [Results] The SCI and stroke groups had lower VC than the control group; the SCI group had the lowest value. The stroke group had the lowest FVC. There were no significant differences among the three groups in FEF, FEV1, or FEV1/FVC. The ADL of the SCI group showed significant differences according to the SCI level. Regarding the relationship between respiratory function and ADL, in the SCI group, the better their respiratory function was, the better their ADL became; there was no relationship between the two variables in the stroke group. The control group of healthy elderly was better able to climb stairs when they had better respiratory function. [Conclusion] We consider a physical therapy program accompanied by breathing execercise is necessary for SCI patients to improve ADL, and for stroke patients to prevent respiratory complications.