Y-STR test is a test which targets Y chromosome that is common within biologically related men of the same family and so provides to understand whether there is a biological relationship from father side. This test, which is used as an alternative of paternity test when alleged father is not available to participate in test, is performed with samples taken from the child and men who are biological relatives of the alleged father. After permissions of participants and official parents of under 18 years old children are taken, mouth swab samples are taken easily by participants with cotton swabs sent by us and they are sent back to the laboratory. After samples are reached to the laboratory, samples are examined with Y-STR marker and results are ready in 5 workdays. Results cannot be used as evidence in courts.