Five members of a family with dominantly inherited diabetes insipidus were diagnosed and treated with deamino-d-arginine vasopressin (DDAVP), a vasopressin analogue given intranasally. All subjects demonstrated subnormal levels of arginine vasopressin (AVP) by radioimmunoassay in response to cigarette smoke inhalation, a standardized nicotine stimulation test. Levels of oxytocin (OT) were found to be normal and unstimulated after cigarette inhalation in two subjects, but when two affected male siblings ingested Ovulen, OT and ESN were stimulated to subnormal levels. After twelve months of DDAVP treatment, the low AVP response to nicotine was preserved whereas the carrier protein, nicotine stimulated neurophysin (NSN) remained undetectable.