Background: Idiopathic pulmonary fibrosis (IPF) is a chronic, devastating, interstitial lung disease, with few therapeutic options. IPF is characterized by pulmonary restriction, dyspnea, hypoxemia, exercise intolerance and poor quality of life (QOL). Objectives: We aimed to examine the effect of exercise training (ET) on clinical outcomes in IPF patients. Methods: A randomized controlled study included thirty-two IPF patients (aged 68 ± 8 years) who were allocated either to the ET group (n = 15), participating in a 12-week, twice-weekly 60-min supervised ET-based pulmonary rehabilitation program, or to a control group (n = 17) continuing with regular medical treatment alone. Cardiopulmonary exercise test, 6-min walking distance (6MWD) test, 30-second chair-stand test, pulmonary function tests, dyspnea and QOL were assessed at baseline and at the end of the 12-week intervention. Results: Significant differences were observed between the ET and the control groups in raw mean deltas (Δ = post- - pre-intervention): Δ6MWD, 81 m, p < 0.001; ΔVO2 peak, 2.6 ml/kg/min, p = 0.002; Δwork rate, 22 W, p < 0.001; Δanaerobic threshold, 3.1 ml/kg/min, p < 0.001, and ΔFVC % predicted, 6%, p = 0.038. Dyspnea, QOL and 30-second chair-stand were also improved significantly following the program. Conclusions: ET improves exercise tolerance, functional capacity, pulmonary function, dyspnea and QOL in patients with IPF, suggesting a short-term treatment efficacy for clinical improvement, and should be considered the standard care for IPF.