The field of Molecular Biology continues to attract and excite the students of all branches of life sciences, including biology and Medicine.The text covers two basic but very important aspects of Molecular Biology, DNA structure and replication. Some of the aspects of DNA structure which the beginners usually find difficult to follow and understand from the usual texts have been discussed and simplified. DNA replication in prokaryotic organisms has been explained. Eukaryotic DNA and its replication has also been covered. The text though appears comprehensive is basically meant for the beginners.