Ernesto Contreras (1915–2003) served as a Mexican medical doctor. He operated the Oasis of Hope Hospital in Tijuana for over 30 years, claiming to "treat" cancer patients with amygdalin (also called "laetrile" or, erroneously, "vitamin B17") which has been found completely ineffective. His practices have been widely condemned. Contreras received post-graduate training at the Children's Hospital Boston in Boston. He served as the chief pathologist at the Army Hospital in Mexico City and was Professor of Histology and Pathology at the Mexican Army Medical School.