In five members of three generations in a family studied in 1972, 3 nephrological disorders occurred concurrently: distal renal tubular acidosis (dRTA), polycystic kidney and nephrogenic diabetes insipidus (with the exception of a five-year-old child in whom polycystic kidney was not detectable--yet?). Chromosoma studies revealed an increased rate of the occurrence of variations. The youngest patient was reinvestigated in 1993; the other four affected members of the family were already not alive. 7 offsprings in two generations of the 3 healthy members of the third "patient generation" were healthy. The autosomal dominant way of inheritance characteristic to both dRTA and polycystic kidney disease was obvious in this family. On the other hand the same degree of the concentrating defect found both in the patients of the familial dRTA and in 11 control patients with non familial (acquired) dRTA suggested that the nephrogenic diabetes insipidus as an acquired disorder was associated with the two congenital abnormalities. The clinical picture of the combined disease was dominated by the symptoms of polydipsia and polyuria. The vasopressin resistance with a variation in the degree interindividually seemed to be responsible for the nephrogenic diabetes insipidus. Functional insufficiency of the loop of Henle was excluded on the basis of normal responses to a "loop diuretic".