Invasive aspergillosis (IA) are a major complication in immunocompromized patients where can be serious and rapidly fatal. Early diagnosis and early appropriate antifungal treatment is important in reducing mortality and morbidity. But despite many efforts to develop detection methods, the diagnosis of IA still remains challenging and current conventional methods are limited for adequate diagnosis. New rapid methods which can detect IA early in the course of disease with high sensitivity and specificity are needed since treating these infections at an early stage. Using molecular methods for Aspergillus species identification can be a cost-effective, rapid, discriminatory, and objective approach for delineating Aspergillus species in a clinical microbiology laboratory. PCR techniques for the diagnosis of IA have been studied for more than a decade and are still considered investigational, however until now PCR is not included in current EORTC/MSG diagnostic criteria.