The purpose of this investigation was to study subjective symptoms, medical and social situation, pulmonary function and physical work capacity over a period of 3-5 years in patients with post-polio syndrome. We assessed a consecutive series of 68 patients admitted to our hospital because of post-polio syndrome, and re-assessed 63 of these patients 3-5 years later; 43 women and 20 men with mean age 55 +/- 10 (1 SD) years at the second evaluation. The patients answered a questionnaire about their subjective symptoms and medical and social situation, and underwent spirometry and symptom-limited exercise stress testing. Most patients experienced more serious symptoms and physical disability connected with their polio, while the majority reported that their psychological health was unchanged or had improved. Lung function was on average moderately reduced and of restrictive type, and only minor changes were found over the 3-5 years. A pronounced reduction in peak oxygen uptake was seen at the first evaluation, especially in women (59% of predicted). At the second examination, peak oxygen uptake was further reduced, especially in men, more than predicted by increasing age. The body weight and body mass index of the patients increased significantly during the same period. These results indicate that subjective symptoms and physical disability connected with polio increased with increasing age in these patients with post-polio syndrome, and cardio-respiratory deconditioning and weight gain also became more serious problems in most patients. The psychological status of the patients remained stable, however, or improved, possibly due to our comprehensive re-rehabilitation and educational programme.