The mean serum concentration of 25-OH-D was significantly higher in the reference group (57.6 ± 23 nmol/L) compared with the COPD group (51.5 ± 22 nmol/L) (P = 0.039). The dietary intake was predominantly below the recommendations in both groups. Mean total daily intake of vitamin D and mean daily supplementation of vitamin D was significantly higher in the COPD group (P = 0.012 and P = 0.030, respectively). Low intake of vitamin D and low serum levels of 25-OH-D are common in both COPD patients and an elderly Swedish population. Monitoring vitamin D status and possibly routinely treating COPD patients with vitamin D and calcium should be considered to minimise the risk of severe vitamin D deficiency among COPD patients.