Spontaneous hyponatremia in cirrhosis with ascites is generally considered to be due to an impaired renal ability to excrete free water, to be a contraindication of diuretics, and to be a bad prognostic sign. These concepts are reviewed in this paper. 55 cirrhotics with ascites were divided into three groups. Group I consisted of 13 patients with hyponatremia and very low free-water clearance ( C_{H2 O}C_{H_2 O} , 0.07±0.26 ml/min). These patients also had poor renal function: low inulin clearance (C _INU , 40.6±25.9 ml/min) and paraamino-hippurate clearance (C _PAH , 383±275 ml/min). Group II consisted of 8 patients who also had hyponatremia. C_{H2 O}C_{H_2 O} , C _INU , and C _PAH in these patients were fairly high: 5.85±1.53 ml/min, 85.7±26.2 ml/min, and 651±294 ml/min. These values are similar to those of the 34 patients without hyponatremia who make up Group III: (6.37±4.27 ml/min, 94.7±33.1 ml/min, and 598±199 ml/min). Hyponatremia in Group I could be related to the impaired free-water clearance. The mechanism of hyponatremia in Group II patients is not clear. Patients with hyponatremia and low C _INU and C _PAH had a negative response to diuretics and a poor prognosis. Patients with hyponatremia but with relatively good renal function had a good prognosis, similar to Group III patients. They responded to diuretics with no worsening of their hyponatremia.