Streptomyces coelicolor A3(2) and Escherichia coli are quite different in their life-style and the structures of their genomes. Streptomyces exhibit complex multicellular development including formation of multigenomic hyphae during growth. These organisms possess a large linear (8.7 Mb) and GC-rich (~72%) chromosome. The genome sequence of S. coelicolor has just been completed. The difference between E. coli and Streptomyces making them an excellent model organisms for a comparison of their replication modes. In this review, we compare initiation of chromosome replication in both organisms. Their replication origins are different in size, but both have DnaA boxes ? a binding motifs for initiator DnaA protein. The two DnaA proteins have practically the same biochemical properties. Many aspects of the control of initiation seem to be similar. A comparison of the two systems thus allows us to define those aspects of replication initiation that are universally used in the eubacterial kingdom.