Spironolactone and furosemide, which are used to treat ascites associated with decompensated cirrhosis, are ineffective in treating refractory ascites. Hence, combination therapy with tolvaptan, a vasopressin V2 receptor antagonist, has been approved in Japan. Tolvaptan monotherapy and combination therapy with furosemide inhibit fibrosis in cardiac remodeling; hence, we examined these therapies in a rat cirrhotic model, including their usefulness in inhibiting hepatic fibrosis. In the present study, we used a model of hepatic fibrosis induced by a choline-deficient l -amino-acid-defined diet + diethylnitrosamine. Rats were divided into a low-dose furosemide group (15 mg/kg/day), a high-dose furosemide group (100 mg/kg/day), a tolvaptan monotherapy group (10 mg/kg/day), a low-dose furosemide/tolvaptan combination therapy group, and a control group which received neither furosemide nor tolvaptan; we then assessed diuretic effects and hepatic fibrosis. The tolvaptan monotherapy group and the furosemide/tolvaptan combination therapy group demonstrated significantly higher urine volume than the control group and the low-dose furosemide group. In addition, tolvaptan monotherapy and low-dose furosemide/tolvaptan combination therapy were found to inhibit hepatic fibrosis and yield a hepatoprotective effect by an antioxidative mechanism. The results of the present study suggest that tolvaptan monotherapy and low-dose furosemide/tolvaptan combination therapy are highly effective for hepatoprotection and diuresis.