Critically ill chronic obstructive pulmonary disease (COPD) patients who are admitted to intensive care units (ICU) are at particular risk for invasive pulmonary aspergillosis (IPA). The objective of this investigation was to assess the value of consecutive galactomannan (GM) tests in determining the diagnosis and prognosis of IPA in this patient population. We studied 90 critically ill COPD patients admitted to our ICU between February 2007 and November 2009. Two consecutive serum GM tests were done on the first and fourth days of their ICU admissions. Patients were classified as proven IPA (n = 1), probable IPA (n = 18), or non-IPA (n = 71). The sensitivities, specificities, and positive and negative predictive values of GM test results for (i) the first test, (ii) the second test, (iii) at least one positive of two consecutive tests and (iv) two positive consecutive GM tests were, respectively, 57.9%/64.7%/70.6%/47.1%; 87.3%/84.6%/80.8%/94.2%; 55.0%/57.9%/54.5%/72.7%; and 88.6%/88.0%/89.4%/84.5%. The mortality values of IPA patients with (i) a positive first GM test, (ii) at least one of two tests positive, and (iii) both tests positive were (a) 81.8% (9/11), (b) 83.3% (10/12), and (c) 72.7% (8/11), respectively. These results indicate that at least one positive result of two consecutive GM tests appears to be useful in the diagnosis of IPA in critically ill COPD patients in an ICU. In addition, positive serum GM results combined with the isolation of Aspergillus from respiratory samples may be a potential marker of high mortality.