An alkalitolerant actinomycete strain, designated EGI 80425T, capable of producing ansamitocin P-3, was isolated from a saline-alkali soil sample of Xinjiang province, north-west China, and subjected to a polyphasic taxonomic characterization. Strain EGI 80425T formed non-fragmented substrate mycelia and white aerial hyphae with long spore chains. Whole-cell hydrolysates of the isolate contained meso-diaminopimelic acid as the diagnostic diamino acid and rhamnose as the major sugar. The major fatty acids were anteiso-C17 : 0, iso-C16 : 0 and C18 : 1ω9c. The predominant menaquinones were MK-10(H4), MK-10(H6), MK-10(H8) and MK-9(H4). The G+C content of the genomic DNA of strain EGI 80425T was 70.2 mol%. Strain EGI 80425T showed highest 16S rRNA gene sequence similarity to Nocardiopsis dassonvillei subsp. dassonvillei DSM 43111T (96.44 %). Phylogenetic analysis showed that strain EGI 80425T clustered with the members of the genus Nocardiopsis. Based on phenotypic, chemotaxonomic and phylogenetic characteristics, strain EGI 80425T represents a novel species of the genus Nocardiopsis, for which the name Nocardiopsis ansamitocini sp. nov. is proposed. The type strain is EGI 80425T ( = CGMCC 9969T = KCTC 39605T).