The binding of tritium-labelled arginine vasopressin to human platelet vasopressin receptors was investigated in patients with congenital nephrogenic diabetes insipidus. Binding characteristics, that is receptor affinity and the maximum number of binding sites, were not significantly different from those found in normal control individuals. The findings confirm the concept of intact V1 receptors in congenital nephrogenic diabetes insipidus. The defect in nephrogenic diabetes insipidus apparently only affects the cyclic adenosine monophosphate dependent V2 receptors.