[Purpose] To evaluate the effects of kyphosis on swallowing and respiratory functions. [Participants and Methods] In 94 healthy adult volunteers, the respiratory (vital capacity, percentage of vital capacity, and cough peak flow and swallowing (hyoid amplitude and tongue pressure) functions, were evaluated under the following conditions: vertical, moderate kyphosis, and severe kyphosis postures defined by the round-back index. [Results] The mean vital capacity and percentage of vital capacity were significantly lower in severe kyphosis than in the vertical posture. The suprahyoid muscle amplitudes, tongue pressure, and cough peak flow was significantly lower in severe kyphosis than in moderate kyphosis or the vertical positions. [Conclusion] The swallowing and breathing functions were significantly lower in volunteers with severe kyphosis than in those with moderate kyphosis or the vertical positions. Although strengthening of the suprahyoid muscles is a typical example of rehabilitation for dysphagia, but it may also be necessary to consider postural adjustment for patients with kyphosis. A comprehensive evaluation of swallowing function that takes both posture and respiratory function into consideration is necessary.