Invasive aspergillosis is a serious problem for immunocompromised patients, especially if neutropenic. The diagnosis of this infection is complicated, since clinical symptoms are often similar to those of other fungal diseases. The chance of detecting the presence of a specific antigen in the serum could confirm the suspected clinical diagnosis and. perhaps, be useful for the follow-up of the patient. The Medical Mycology Committee of the Associazione Microbiologi Clinici Italiani (AMCLI) decided to evaluate in a multicenter prospective study (from I November 1998 to 28 February 1999) the performance of the Platelia Aspergillus Kit (Bio-Rad) for the detection of Aspergillus galactomannan in human serum. The enrolled patients included various groups of immunosuppressed patients (mostly neutropenic). Blood samples were drawn at the time of enrollment. This decision was based upon a clinical diagnosis of probable aspergillosis (antibiotic non-responsive fever for at least 96 hours, cough, hemophthosis and positive chest X-ray). Additional blood samples were drawn on days 3, 6, 9, 12, 15 and 21. Culture and histopathologic examinations were performed according to the individual laboratory workflow. For each patient the laboratory filled a form with all the available clinical information, to create a database on which to evaluate the results of the test. During the study, 187 patients with various kinds of immunosuppression were enrolled. A total of 256 sera were tested: for 117 patients (62.6%) only the basal sample was tested, whereas for the 70 symptomatic patients (37.4%) multiple specimens (range: 1-6) were tested. The results allowed the laboratories to exclude (68.6%) or confirm (31.5%: confirmed and/or probable) the clinical diagnosis of invasive aspergillosis; 4 cases remained undetermined. Based on the results of this study, it seems that the use of this test should be limited to those patients with clinical symptoms of aspergillosis.