The taxonomic positions of two novel actinomycetes, designated strains BNT558(T) and SM3501(T), were established by using a polyphasic approach. The organisms had chemical and morphological features that were consistent with their classification in the genus Streptomyces. The whole-cell hydrolysates of the two strains contained LL-diaminopimelic acid as the diagnostic diamino acid. The predominant menaquinones were MK-9(H-6) and MK-9(H-8) for strain BNT558(T) and MK-9(H-8) and MK-9(H-6) for strain SM3501(T). Major fatty acids of the strains were anteiso-C-15:0, anteiso-C-17:0 and iso-C-(16:0). The polar lipid profile of strain BNT558(T) contained diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, one unidentified glycolipid and one unidentified aminophospholipid, while that of strain SM3501(T) consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine, three unidentified atypical aminolipids, one unidentified aminolipid and two unidentified glycolipids. The G+C contents of the genomic DNA were 70.2 and 69.6 mol% for strains BNT558(T) and SM3501(T), respectively. 16S rRNA gene sequence data supported the classification of the isolates in the genus Streptomyces and showed that they formed two distinct branches within the genus. Based on almost-complete 16S rRNA gene sequences, strain BNT558(T) was related most closely to Streptomyces albiaxialis NRRL B-24327(T) and strain SM3501(T) was related most closely to Streptomyces cacaoi subsp. cacaoi NBRC 12748(T). DNA-DNA relatedness between each of the isolates and its closest phylogenetic neighbours showed that they belonged to distinct species. The two isolates were readily distinguished from one another and from the type strains of the other species classified in the genus Streptomyces based on a combination of phenotypic and genotypic properties. Based on the genotypic and phenotypic evidence, strains BNT558(T) and SM3501(T) belong to two novel species in the genus Streptomyces, for which the names Streptomyces iconiensis sp. nov. (type strain BNT558(T)=KCTC 29198(T)=DSM 42109(T)) and Streptomyces smyrnaeus sp. nov. (type strain SM3501(T)=KCTC 29214(T)=DSM 42105(T)) are proposed, respectively.