Amniocentesis and fetal skin biopsies were performed at 18 weeks of gestation in a fetus at risk for autosomal dominant polycystic kidney disease (ADPKD) and autosomal recessive junctional epidermolysis bullosa (EBJ) with pyloric atresia. A previous son of the couple under investigation had died at 3 months of EBJ. The mother of the propositus has ADPKD. Genetic linkage studies were carried out in 11 relatives (4 with ADPKD), and on fetal DNA obtained from cultured amniocytes, using 8 flanking DNA markers tightly linked to the PKD1 locus on chromosome 16p, and a DNA marker linked to another putative ADPKD locus on chromosome 2p. The linkage results indicated that the fetus had not inherited the ADPKD chromosome from the affected mother, with a diagnostic accuracy of > 99%. Ultrastructural and immunohistochemical analyses of multiple fetal skin biopsies showed no EBJ-associated abnormalities. Thus, combining recent morphological and molecular diagnostic methods, we could show that the fetus was free from both diseases. After 40 weeks of gestation, a normal male infant was delivered.