Invasive Aspergillus infection (IAI) occasionally occurs in immunocompromised people. Except administrating empirical anti-fungal agent, using objective parameters to support the tentative diagnosis of an IAI in order to make the anti-fungal treatment more specifically is also important. At present, serum galactomannan (GM) test is the less-invasive, non-cultural, and time-saving examination for augmenting a diagnosis of Aspergillosis. It was suggested by Infectious Disease Society of America (IDSA) 2008 as a screening and monitoring tool for Aspergillosis , and the cut-off value was adjusted to 0.5 by USA FDA . However, in clinical practice, GM seems not to have good predicted value even the sensitivity and specificity are declaimed more than 80% . Other controversial issues include the reproducibility of GM5 and the effect of piperacillin-tazobactam or other antibiotics on the accuracy of GM baseline In this study, serum GMs are examined in two conditions, one is collected for establishing a baseline and the other is collected after piperacillin-tazobactam administration. We hope to confirm the validity of GM baseline and the effect of piperacillin-tazobactam on GM value in Taiwan.