A filamentous actinomycete strain, designated GW9-2(T), was isolated from a soil sample collected from the Fildes Peninsula, King George Island, West Antarctica. The strain was identified using a polyphasic taxonomic approach. The strain grew slowly on most media tested, producing small amounts of aerial mycelia and no diffusible pigments on most media tested. The strain grew in the presence of 0-12 % (w/v) NaCl (optimum, 2-4 %), at pH 9.0-11.0 (optimum, pH 9.0) and 10-37 °C (optimum, 28 °C). The isolate contained meso-diaminopimelic acid, no diagnostic sugars and MK-9(H4) as the predominant menaquinone. The major phospholipids were phosphatidylglycerol, phosphatidylcholine and phosphatidylmethylethanolamine. The major fatty acids were iso-C16 : 0, anteiso-C17 : 0, C18 : 1ω9c, iso-C15 : 0 and iso-C17 : 0. DNA-DNA relatedness was 37.6 % with Nocardiopsis lucentensis DSM 44048(T), the nearest phylogenetic relative (97.93 % 16S rRNA gene sequence similarity). On the basis of the results of a polyphasic study, a novel species, Nocardiopsis fildesensis sp. nov., is proposed. The type strain is GW9-2(T) ( = CGMCC 4.7023(T) = DSM 45699(T) = NRRL B-24873(T)).