The aim of our study was evaluation of C-reactive protein (CRP) levels in patients with COPD exacerbation. We studied 38 COPD patients with clinical evidence of exacerbation and 21 COPD patients in a steady clinical state from the outpatient department. The patients in exacerbation were evaluated by chest x-ray, white blood cell count, sputum cultures, PaO2 levels and CRP blood levels.There was a statistical increase in the values of CRP of the patients in exacerbation, in comparison with those being in a steady state (p<0.001). There was no correlation between the CRP values of patients in exacerbation and their PaO2 values. There was statistical correlation between the values of CRP and the white blood cell count in those patients (R=0.469 p<0,01). Only six sputum cultures were positive for pathogens. CRP is of value in the assessment of exacerbations of COPD, where routine bacterial culture of sputum is often unreliable, but it is not necessarily a marker of bacterial infection "per se". Pneumon 2001, 14 (1): 70-73