Ligation refers to the joining or ligating of two nucleic acid fragments through the action of an enzyme. The attaching of blunt-ended DNA fragments by the enzyme DNA ligase is known as blunt end ligation.

This is a crucial laboratory procedure used in the molecular cloning of DNA. During the process the linearized plasmid vector and the blunt-ended insert are mixed with DNA ligase. The reaction gets initiated when the vector, insert and ligase come together in solution. A major advantage of blunt-end cloning is that the desired insert does not require any restriction sites in its sequence as blunt-ends are usually generated in a PCR, and the PCR generated blunt-ended DNA fragment may then be ligated into a blunt-ended vector generated from restriction digest.