A genealogical DNA test is a DNA-based genetic test used in genetic genealogy that looks at specific locations of a person's genome in order to find or verify ancestral genealogical relationships, or to estimate the ethnic mixture of an individual. Since different testing companies use different ethnic reference groups and different matching algorithms, ethnicity estimates for an individual vary between tests, sometimes dramatically.

Genetic genealogy is the use of genealogical DNA tests, i.e., DNA profiling and DNA testing, in combination with traditional genealogical methods, to infer genetic relationships between individuals. This application of genetics came to be used by family historians in the 21st century, as DNA tests became affordable. The tests have been promoted by amateur groups, such as surname study groups or regional genealogical groups, as well as research projects such as the Genographic Project.