Rheumatic diseases are chronic inflammatory diseases which cause mild to severe functional loss and disability due to articular and extra-articular manifestations. One common form -ankylosing spondylitis (AS)- affects mainly the axial skeleton and sacroiliac joints, and certain extra-articular organs. The pulmonary involvement is a known manifestation of AS and emerges either in the form of interstitial lung disease or in the form of restricted pulmonary functions. The aim of this study is to determine the pulmonary functions in AS patients and to assess its relationship with quality of life, functionality and disease activity. Thirty-six AS patients and 34 healthy volunteers were recruited for the study. A detailed examination, pulmonary function tests, smoking inquiry and quality of life questionnaire were performed on all participants. Also patients were requested to complete functionality and disease activity indexes. The outcomes showed that 15 (41.7%) AS patients had pulmonary involvement: twelve patients with restrictive patterns, one with obstructive pattern, and two with both restrictive and obstructive patterns. Decreased forced expiratory volume in one second was associated with deteriorated functionality (p < 0.05). Decreased chest expansion was also accompanied with decreased forced vital capacity (p < 0.05). There was no statistically significant difference between the smoking and non-smoking patients in regard to disease activity, functionality and pulmonary function test variables (p > 0.05). In conclusion, the pulmonary involvement is common in AS and might have disturbed functionality and the quality of life in AS patients.