Endeavor, the new nationwide health care law is being implemented in stages. One of the first stages, implemented in 2010, is making sure children younger than age 18 are not denied health care coverage because of pre-existing conditions. Also, children can now remain on their parent's health care policies until age 26.
By the time you are 26, another phase of the new health care law will have kicked in, which consists of ensuring that no adult is denied because of a pre-existing condition.