Semiconservative replication describes the method by which DNA is replicated in all known cells. This method of replication was one of three proposed models of DNA replication:

• Conservative replication would leave the original, template DNA strands intact and would produce a copy composed of entirely new DNA base pairs.
• Dispersive replication would produce two copies of the DNA, both containing a mixture of old and new DNA base pairs.
• Semiconservative replication would produce two copies that each contained one of the original strands, and one entirely new copy.

The deciphering of the structure of DNA by Watson and Crick in 1953 suggested that the semiconservative model was correct (as Watson and Crick pointed out in a one-line concluding sentence to their seminal paper). This was soon verified by the Meselson-Stahl experiment.