With the developments in taxonomy, the classically used highly conserved 16S rRNA molecular marker has shown some disadvantages among closely related species. For further taxonomic studies of the prokaryotes, specific PCR primers were designed from two conserved regions in the amino acid sequences of the 70-kDa heat shock protein sourced from 20 different genera in actinomycetes. These were used for the amplification of the hsp70 genes in 16 Streptomyces strains. Then, we investigated the phylogenetic relationships among these Streptomyces strains and compared the tree topology based on the hsp70 gene with those based on the previously used markers (16S rRNA and gyrB). To our knowledge, this is the first use of the hsp70 gene as a molecular marker for the taxonomic identification of Streptomyces.