The interpretation of a condition in genetically unusual circumstances is often handicapped by an atypical presentation, unusual course (variable penetrace?), or incomplete pedigree information, in addition to the constant hazard of unknown illegitimacy. For these reasons, the thorough study of two American Indian families with cystic fibrosis of the pancreas (Harris and Riley, Pediatrics, 41:733, 1968) is particularly valuable. The report prompted us to review the less satisfactorily documented non-caucasian patients with cystic fibrosis autopsied in the Johns Hopkins Hospital.