Michelle Cedillo v. Secretary of Health and Human Services, also known as Cedillo, was a court case involving the family of Michelle Cedillo, an autistic girl whose parents sued the United States government because they believed that her autism was caused by her receipt of both the measles-mumps-and-rubella vaccine (also known as the MMR vaccine) and thimerosal-containing vaccines. The case was a part of the Omnibus Autism Proceeding, where petitioners were required to present three test cases for each proposed mechanism by which vaccines had, according to them, caused their children's autism; Cedillo was the first such case for the MMR-and-thimerosal hypothesis.