Although a great amount of information is available on bacteria inhabiting deep-sea sediments, the occurrence of fungi in this environment has been poorly studied and documented. We report here the occurrence of fungi in deep-sea sediments from ~5000 m depth in the Central Indian Basin (9-16oS and 73-76oE). A total of 181 cultures of fungi, most of which belong to terrestrial sporulating species, were isolated by a variety of isolation techniques. Species of Aspergillus and non-sporulating fungi were the most common. Several yeasts were also isolated. Maximum species diversity was observed in 0-2 cm sections of the sediment cores. Direct staining of the sediments with Calcofluor, a fluorescent optical brightener, revealed the presence of fungal hyphae in the sediments. Immunofluorescence using polyclonal antibodies raised against a deep-sea isolate of Aspergillus terreus (# A 4634) confirmed its presence in the form of hyphae in the sub-section from which it was isolated. A total of 25 representative species of fungi produced substantial biomass at 200 bar pressure at 30o as well as at 5oC. Many fungi showed abnormal morphology at 200 bar/5oC. A comparison of terrestrial isolates with several deep-sea isolates indicated that the former could grow at 200 bar pressure when growth was initiated with mycelial inocula. However, spores of a deep-sea isolate Aspergillus terreus (# A 4634), but not the terrestrial ones, showed germination at 200 bar pressure and 30oC. Our results suggest that terrestrial species of fungi transported to the deep sea are initially stressed but may gradually adapt themselves for growth under these conditions.