Two actinomycete strains, designated N7-3T and N4-6T, were isolated from a natural cave on Jeju Island, Republic of Korea, by using a dilution method, and were subjected to physiological, chemical and molecular characterization. The nearly complete sequences of the 16S rRNA gene were aligned and compared with those of representatives of the genus Amycolatopsis. Phylogenetic analysis showed that the organisms belong to the family Pseudonocardiaceae and formed two distinct lineages within the evolutionary radius of the genus Amycolatopsis. The chemotaxonomic and morphological properties support their classification in the genus Amycolatopsis. The 16S rRNA gene sequence data revealed that the closest relatives of strains N7-3T and N4-6T were Amycolatopsis sulphurea (97.9% similarity) and Amycolatopsis albidoflavus (98.7% similarity), respectively. The combination of physiological and genetic data supported the observation that the organisms could be distinguished from each other and from established species of the genus Amycolatopsis. The names Amycolatopsis jejuensis sp. nov. and Amycolatopsis halotolerans sp. nov. are proposed for the two novel species, with N7-3T (= NRRL B-24427T = JCM 13280T) and N4-6T (= NRRL B-24428T = JCM 13279T) as the respective type strains.