As the number of cases of aspergillosis grows, the number of species reported to cause the disease is increasing. Historically, classification and identification of aspergilli was accomplished using morphological characteristics. A number of molecular, immunological and biochemical methods are now available. For the most part, the results of the various approaches concur, yielding similar results in identifying aspergilli, so the 'best' method for identification is the method that best suits the needs of the researcher or clinician. Each identification method has advantages and disadvantages which will be discussed herein. The paper contains a listing of some of the available identification systems from those that address the whole genus to those capable of separating intraspecific strains.