Change in the base sequence of a genome that has little effect on fitness of the so-affected organism as compared with the parental sequence.

Neutral mutations simply are mutations that don't significantly modify an organism's ability to and/or reproduce. See also allele.

See, similarly, neutral allele, neutral variation, and . Contrast with beneficial mutation and beneficial allele. Contrast also with detrimental allele as well as deleterious allele and even lethal allele.