Publisher Summary This chapter discusses that a variety of scientific disciplines have been applied to the quest of discovering the structure of DNA is replicated. Over the years, a large store of permanent physical, biochemical, and biological information has been gathered about DNA and the manner of its replication. The chapter summarizes the most recent findings concerning replication. It discusses the two developments: First, information is accumulating about the microscopic events at the growing region of DNA. Second, the recent genetic experiments that firmly advances the possibility of the enzyme DNA polymerasc of Escherichia coli (E.coli). With these developments, to again examine certain features of a number of models proposed for DNA replication seems worthwhile, that, at present, do not seem trivial. The chapter also discusses the biochemical direction, dealing chiefly with the problems of DNA synthesis during replication. The mechanical problems inherent in replicating a double helix are also discussed briefly, although, they pose a formidable problem and have received considerable scholarly attention. Most of the information cited conies from experiments on bacteria and the viruses that infect them.