Fungi are known to produce a range of extracellular enzymes and other secondary metabolites. Investment in extracellular enzyme production may be an important element of the survival strategy of these fungi in maritime Antarctic soils. This study focuses on fungi that were isolated from ornithogenic, undisturbed and human-impacted soils collected from the Fildes Peninsula, King George Island, Antarctica, during the austral summer in February 2007. We (1) describe fungal diversity based on molecular approaches, (2) describe the thermal characteristics of the fungal isolates, and (3) screen extracellular hydrolase enzyme production (amylase and cellulase) by the isolates. Soil samples were cultured using the Warcup soil plating technique and incubated at 4 and 25 degrees C to allow basic thermal classification. In total, 101 isolates were obtained. All the isolates were screened at culture temperatures of 4 and 25 degrees C in order to detect activity of extracellular hydrolase enzymes. At 25 degrees C, ornithogenic penguin rookery soils recorded the lowest diversity of fungi, with little difference in diversity apparent between the other soils examined. At 4 degrees C, an undisturbed site recorded the lowest and a human-impacted site the highest diversity of fungi. The majority of the fungi identified in this study were in the mesophilic thermal class. Six strains possessed significant activity for amylase and 13 for cellulase at 25 degrees C. At 4 degrees C, four strains showed significant amylase and 22 significant cellulase activity. The data presented increase our understanding of microbial responses to environmental temperature.