P>Invasive aspergillosis (IA) presents a diagnostic and therapeutic dilemma for the physicians who take care of the patients with severe underlying diseases and immunosuppression. This study aimed to evaluate the usefulness of serum galactomannan (GM) measurements in the routine practice and surveillance of IA along with possible caveats in diagnosis and treatment. Adult patients with high-risk haematological malignancies admitted to the Internal Medicine wards during the 2-year study period were followed up by daily visits for vital signs, existing or newly developing signs and symptoms, clinical and laboratory findings. Blood samples were analysed for GM levels by the ELISA method at the end of the study period. Data of 58 hospitalisation episodes in 45 patients were analysed. Proven IA was diagnosed in one patient, probable IA was diagnosed in four patients. The sensitivity was 60% and the specificity was 21% when the index cut-off for positivity was accepted as 0.5. The yield of GM testing may be influenced by many variables and each centre should evaluate the usefulness of this test in its own conditions.