One of the most problematic issues in hematological malignancies is the diagnosis of invasive fungal diseases. Especially, the difficulty of mycological diagnosis and the necessity of immediate intervention in molds have led to the adoption of 'surrogate markers' which does not verify, but strongly suggests fungal infection. The markers commonly used are galactomannan (GM), beta-glucan and imaging methods. Although there are numerous studies on these diagnostic approaches, none of these markers serve as a support for the clinician, as is in human immunodeficiency virus (HIV) or cytomegalovirus (CMV) infections. This paper has been prepared to explain the diagnostic tests and show the clinician how the available resources can be used. As moleculer tests have not been standardized and not used routinely in the clinics, they will not be mentioned here.