IN seven members of four related Amish sibships, each bearing the name Byler, a disorder characterized by intrahepatic cholestasis has been identified.1The purpose of the present report is to describe the clinical, biochemical, and histologic findings. Pedigree pattern and demonstration of biochemical abnormality in four presumed heterozygotes are evidence of the autosomal recessive nature of the syndrome. Report of Cases Case1.—A girl born in 1947 (VI,5 in Fig 1) was noted from early infancy to have loose, foul-smelling stools. At 9 months, jaundice was observed which subsequently cleared. For the next two years she had recurrent bouts of jaundice associated with light stools, dark urine, and pruritus. The "attacks" were often associated with infection and the jaundice persisted for periods varying from two weeks to two months. At 2 ⅔ years she was hospitalized for laparotomy. An enlarged lymph node thought to be compressing the common bile