Since the DNA is the same in every cell in an individual, the genetic material utilizable to carry out the test can be taken from various tissues. Normally, testing is carried out with a peripheral blood sample. To permit DNA sampling of a newborn baby, the amount of blood necessary is very small (even a few drops of dried blood). A newborn can also be analyzed at birth by the use of a blood sample taken from the umbilical cord.

For a prenatal DNA test, fetal cells (chorionic villi or amniotic fluid). Thanks to sophisticated and sensitive analyltcal methods, the paternity test can also be carried out on biological samples different from traditional ones, even when the biological samples are obtained with non-invasive methods such as an oral swab, hairs, urine, semen, saliva or cells from various tissues. These latter possibilities are very advantageous if children are tiny, and it is best to use the least traumatic method possible.

With the oral swab, the analysis is carried out on cells derived from within the mouth that are harvested with a cotton swab or the bristles of a toothbrush. This method is less invasive and painful than drawing blood and can be carried out on both babies and adults.

Normally the number of cells obtained is enough to carry out the analysis. When the analysis is performed using hair, it is carried out on the cells surrounding the piliferous bulb. For this reason, the hair must be pulled directly from the scalp and not have spontaneously shedded, as for example hairs remaining on a comb or brush.

In the urine and semen, analysis is conducted on the cells contained in the biological liquid. The results obtained by utilizing diverse types of biological materials are perfectly comparable and have the same degree of accuracy.