Adherence to the maintenance exercise program included a 36.7% drop-out rate during the first year after completing PR. Experiencing exacerbations was the most reported reason for dropout. Poorer lung function, shorter initial PR course measured by reviewing patient records, and higher level of depressive symptoms were predictive of drop-out to the maintenance program. Adherence to the maintenance program needs to be improved for patients with lower FEV1, with signs of depression, or with a shorter initial PR course.