Aspergillus Galactomannan Antigen is an important mycotic test used to detect the presence of galactomannan, a cell wall component of Aspergillus fungi, in patient’s biological samples, aiding in establishing the diagnosis of invasive aspergillosis. Aspergillosis manifests as pulmonary, invasive aspergillosis, and neuro aspergillosis, affecting immunocompromised patients. The test is helpful in specific diagnoses, and it initiates an early specific anti-fungal treatment regimen.