A method which allows for the quantitative measurement of DNA in plasma is described. After treatment of plasma with phenol, DNA is precipitated by ethanol using gelatin as a coprecipitating agent. DNA is then measured by nick translation labeling. This assay takes a few hours. It is suitable for the measurement of DNA within a range of 0.02 to 20 ng in 10 microliters of plasma. For example, it is applied to the measurement of DNA in plasma from mice injected with bacterial lipopolysaccharide.