Opportunistic fungal infections are an important cause of morbidity and mortality in immunocom- promised patients. Invasive aspergillosis (IA) has an important place among these infections with ~ 250.000 cases annually. Reducing the mortality rate due to invasive aspergillosis is possible with early di- agnosis and treatment of the disease. Because of the low sensitivity in microscopic examination, the time consuming of culture growth, and the difficulties in distinguishing colonization/infection, serological methods are frequently used in the diagnosis of invasive aspergillosis. The aim of this study was to deter- mine the diagnostic performance of galactomannan and beta glucan tests for the diagnosis of invasive pulmonary aspergillosis (IPA). Sixty patients, followed up with the suspicion of invasive pulmonary as- pergillosis in Gazi University Hospital were included in the study. The clinical classification of the patients was made according to the revised European Organization for Research and Treatment of Cancer and the Mycoses Study Group (EORTC/MSG) criteria. A total of 10 patients were classified as probable invasive aspergillosis and 20 patients were classified as possible invasive fungal disease. Demographic data of the patients and various risk factors were recorded. One hundred and thirty serum and nine bronchoalveolar lavage (BAL) fluid samples were studied with Plateliaᵀᴹ Aspergillus Ag (Bio-Rad, France), Dynamiker As- pergillus Galactomannan and Dynamiker Fungus (1-3)-beta-D-Glucan (Dynamiker, China) kits. Sensitivity and specificity values were calculated according to U.S. Food and Drug Administration (FDA) approved Plateliaᵀᴹ Aspergillus Ag test. According to this study, the most important risk factors in the development of IPA were the use of steroids and immunomodulatory drugs. The sensitivity of the galactomannan test in the probable group was 77.8%, the specificity was 96.7%, the sensitivity of the beta glucan test was 61.1%, and the specificity was 92.6%. When these two tests were evaluated together, it was observed that the sensitivity in the probable group increased to 83.3% and the specificity decreased to 89.3%. The combined use of galactomannan and beta glucan tests increases the diagnostic sensitivity. Although the presence of prolonged neutropenia is an important risk factor for IA, the use of steroids and immu- nomodulatory drugs should be kept in mind in non-neutropenic patients.