The Suk Medical School is a famous place of learning, specializing with medicine. It was claimed that their graduates, like Mentats or Swordmasters of Ginaz, are the best in the Imperium. Suk doctors were thought to have been mentally conditioned in a way that they can never take a human life. In a time rife with kanly, this is a very valuable thing for a trusted doctor. Physically, they are written as having a diamond tattoo on their foreheads as a sign of the Imperial Conditioning and a silver ring binding their long hair. They are first encountered through their student, Wellington Yueh.
In the prequel books, where the character of Yueh was first encountered by the Atreides, it was stated that Suk doctors need not be recruited directly from their home planet or association, as Yueh was serving House Richese when his services were hired by House Harkonnen and House Atreides. It was stated, however, that they remit part of their expensive fees back to the Suk School.