Precise DNA replication is critical for the maintenance of genetic integrity in 
all organisms. In all three domains of life, DNA replication starts at a 
specialized locus, termed as the replication origin, oriC or ORI, and its 
identification is vital to understanding the complex replication process. In 
bacteria and eukaryotes, replication initiates from single and multiple origins, 
respectively, while archaea can adopt either of the two modes. The Z-curve 
method has been successfully used to identify replication origins in genomes of 
various species, including multiple oriCs in some archaea. Based on the Z-curve 
method and comparative genomics analysis, we have developed a web-based system, 
Ori-Finder, for finding oriCs in bacterial genomes with high accuracy. Predicted 
oriC regions in bacterial genomes are organized into an online database, DoriC. 
Recently, archaeal oriC regions identified by both in vivo and in silico methods 
have also been included in the database. Here, we summarize the recent advances 
of in silico prediction of oriCs in bacterial and archaeal genomes using the 
Z-curve based method.