Background and AimUlcerative colitis (UC) patients have several extraintestinal and systemic manifestations. As studies on the frequency and predictors of pulmonary involvement in patients with UC are inconsistent, we undertook this prospective study.MethodsEighty‐seven patients with UC (in remission 49, 56.3%, active disease 38, 43.6%, median age: 40 years, range: 16–66, 55, 62.2% males) and 50 healthy controls (median age: 38 years, range: 14–69, 34, 68% males) underwent pulmonary function tests (PFTs) including forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), Tiffeneau value (FEV1/FVC), mid‐expiratory flow rate, and diffusion lung capacity for carbon monoxide with spirometer.ResultsSubjects with UC and control were comparable in age and gender. PFT was abnormal in 24 (27.5%) patients (active disease 15/38, 39.4%, remission 9/49, 18.4%) and 1 (2%) control (P < 0.005). Of the 24 patients with abnormal PFT, small airway, restrictive, and obstructive defects were detected in 12 (50%), 11 (45.8%), and 1 (4.2%) patients, respectively. Patients with abnormal PFT more often had active disease (15/24, 62.5% vs 23/63, 36.5%; P = 0.03). No relation of PFT abnormalities was found with age, sex, duration of disease, body mass index, serum albumin, and hemoglobin levels, and other extraintestinal manifestation (arthritis/arthralgia) and drugs used to treat UC.ConclusionUC patients with active disease have abnormal pulmonary functions with predominant involvement of small airways. Active UC was more often associated with abnormal PFT than the disease in remission.