半保留复制（Semiconservative replication）是描述DNA的复制方式，目前已知的所有细胞皆以此方式进行复制。是三种主要的复制模型的其中之一，也是唯一确认存在于自然界中的模型。

在此模型中，两条成双链的DNA螺旋会先分开成为两条DNA单链，这两条DNA单链再各自成为复制模板，新的DNA单链合成于其上。因此完成复制之后新的DNA双螺镟分子，各自皆包含了一条新的DNA单链与一条旧的DNA单链。

此概念在证明以前，就已经是个较为合理的解释，因为半保留能使复制出来的两条双螺旋各自保有一个模板。1958年，梅瑟生-史达实验证明了半保留复制。之后则有利用放射性所作的实际观测。

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

The deciphering of the structure of DNA by Watson and Crick in 1953 suggested that each strand of the double helix would serve as a template for synthesis of a new strand. However, there was no way of knowing how the newly synthesized strands might combine with the template strands to form two double helical DNA molecules. The semiconservative model seemed most reasonable since it would allow each daughter strand to remain associated with its template strand. The semiconservative model was supported by the Meselson-Stahl experiment and other even more revealing experiments that allowed for autoradiographic visualization of the distribution of old and new strands within replicated chromosomes.