BACKGROUND Airborne fungi have been surveyed every week during the 20 years from 1993 to 2013 in Sagamihara. This is a follow up of 1983 to 1992 survey at the same sampling station, using the same methods. OBJECTIVE We analyzed the transition of airborne fungi of 20-years. METHODS Using a settle plate method, air sampling was performed by exposing 90 mm settle plates containing potato dextrose agar to the air for 10 min. The plates were incubated at 25℃ for 7-14 days. The fungi were identified and counted. RESULTS The average of number total fungi colonies during 20 years were 507 colony forming units (CFU)/5 plate every year. The most common fungi found, except for yeasts and sterile mycelium, were Cladosporium, Alternaria, Penicillium, Ulocadium, Fusarium, Arthrinium, Epicoccum, Aureobasidium, Curvularia, Nigrospora and Aspergillus. A significant correlation was observed between the number total fungi clonies and number of Cladosporium colonies. Although Alternaria, Arthrinium, Epicoccum and Curvularia were significantly reduced as compared 10 years from 1983 to 1992, Cladosporium and Penicillium were comparable. CONCLUSIONS Cladosporium was most predominant fungi during the 20 years. This study is very valuable in that the transition of airborne fungi revealed by long-term measurement.