BACKGROUND & AIMS: Chronic obstructive pulmonary disease (COPD) has been recognized as a multi component disease. Currently, limited data are available about determining factors of systemic inflammation in COPD, in particular C-reactive protein (CRP). The aim was to determine whether and to what extent COPD patients with a low, high or obese body mass index (BMI) are more likely to have elevated CRP levels compared to normal-weight COPD patients. Furthermore, we aimed to explore the effects of clinically relevant covariates on the likelihood of having elevated CRP levels. METHODS: In 628 elderly patients with moderate to severe COPD (61% male), lung function and BMI were assessed before entering pulmonary rehabilitation. In addition, blood was collected in the fasted state. High-sensitive C-reactive protein (CRP) was classified into: normal, </=3; elevated, >3-5 and highly elevated, >5mg/l. RESULTS: Obese COPD patients (BMI>/=30kg/m(2)) were 3.3 times more likely (95% CI, 1.5-7.0, p=0.002) to have highly elevated CRP levels compared to normal weight (BMI 21-24.9 kg/m(2)) COPD patients after taking clinically relevant confounders into account. In contrast, COPD patients with a low BMI (<21kg/m(2)) were 2 times less likely (OR, 0.5; 95% CI, 0.3-0.9, p=0.022) to have highly elevated CRP levels compared to normal-weight peers. CONCLUSION: Obese BMI is associated with highly elevated CRP levels in patients with COPD. These findings are suggestive for an adipocyte-induced systemic inflammation in COPD.