BACKGROUND In order to evaluate a pulmonary rehabilitation program (PRP) at moderate altitude (1560 m) 62 patients with obstructive lung disease were asked to participate; 37 patients completed a 1-year follow-up at sea level, and 25 patients dropped out. The exercise training program lasted for 10 weeks and consisted of a cycling and running program of 20 min daily, 5 days a week. METHODS Incremental exercise testing, spirometry and histamine provocation tests were performed at sea level before the PRP, on admission to the Dutch Asthma Centre, Davos, after 5 weeks of exercise training, at discharge from the Centre and 6 and 12 months after discharge at sea level. RESULTS The PRP led to an increase in exercise capacity of the 37 patients who also completed the follow-up as reflected by an increase in Wmax (from 104 +/- 44 watt on admission to 150 +/- 8 at discharge, p < 0.001). HRmax (145 +/- 19/min to 151 +/- 21, p < 0.001), Wmax/HR (0.71 +/- 0.26 watt/beat/min to 0.99 +/- 0.29, p < 0.001), VO2max (1.4 +/- 0.4 l/min to 1.9 +/- 0.6, p < 0.001) and VEmax (49 +/- 18 l/min to 78 +/- 24, p < 0.001) measured at discharge from the Dutch Asthma Centre after the PRP were significantly higher than before the PRP at incremental exercise testing. The group of 25 patients who dropped out showed corresponding improvements in these parameters after the PRP in Davos. The 37 patients who completed the follow-up showed at incremental exercise testing 1 year after the PRP that only two of these parameters were still significantly elevated: VO2max 1.8 +/- 0.6 (p < 0.001) and VEmax 61 +/- 21 (p < 0.001). One year after the PRP arterial PCO2 values at maximum exercise were significantly lower (5.2 +/- 0.8 kPa, p < 0.05) than the baseline values (5.5 +/- 0.9 kPa). CONCLUSIONS PRP at moderate altitude results in an increase of exercise tolerance in patients with asthma or COPD, but significant long-term effects are few.