Before the use of DNA testing was wide spread blood testing was used to eliminate potential fathers. Although this process could be useful for determining if a man was not the biological parent of a child, it could not prove that a man was the father with complete certainty. DNA paternity testing on the other hand provides results that are nearly 100% accurate in determining paternity. The results are also admissible in a court of law for determining paternity, custody, inheritance, as well as for settling immigration issues.
The American Pregnancy Organization points out the importance of paternity testing for genetic screening for disease and well-child care.