DeoxybibonucleaseⅠ（DNaseⅠ）was first discovered from cattle pancreas in 1905. Human DNaseⅠ exhibits polymorphisms at both the protein and the DNA levels. DNaseⅠ,preferentially attacking double-stranded DNA to produce oligonucleotides with 5’-phosphoryl and 3’-hydroxy termini, is considered to play a major role in digestion of dietary DNA. Furthermore DNaseⅠhas also been regarded as a candidate endonuclease responsible for internucleosomal DNA degradation during apoptosis and chromatin breakdown of necrotic cells. DNaseⅠ is considered to be one of the susceptibility genes for gastric and colorectal carcinoma, and myocardial infarction and related with the pathogenesis of system lupus erythematosus. With the development of research, DNaseⅠ was used in many fields, including forensic and clinically purposes.It is one of the best biochemical markers for paternity and criminological testing. Clinically, serum DNaseⅠactivity has been recommended to be used as a novel and sensitive marker for the early detection of acute myocardial infarction and transient myocardial ischemia.