Goals: A good response to diuretics is obtained initially in the treatment of cirrhotic ascites. However, unresponsiveness to therapy and various complications may develop with disease progression. This makes obligatory the search for new treatment methods that may be alternative to standard diuretics. In our study, we investigated the effect of mannitol infusion on current therapies in patients with cirrhotic ascites who were using diuretic treatment. Background: Thirty cirrhotic patients with ascites who were using diuretic treatment were included in the study. The patients were randomly divided into two groups; a dose of 100-mL 20% mannitol was administered to the first group, and 100-mL 5 % dextrose solution was administered to the second group. The patients' urinary volumes and serum and urine electrolyte levels (sodium, potassium) were determined before and after the test. Results: In the mannitol group, a significant increase in urinary volume was observed (p < 0.05). However, in the control group no significant differences in urinary sodium excretion were observed after the test (p > 0.05). In the mannitol group, a concomitant increase in urinary volume and sodium excretion was observed in eight cases (53%). The urinary sodium excretions and serum sodium levels before the test were significantly lower in patients who responded to mannitol than in patients who did not respond (p = 0.001 and p = 0.04, respectively). Conclusions: As a result, short-term mannitol therapy makes a significant contribution to diuretic therapy in approximately half of cases with cirrhotic ascites. The results we obtained suggest that mannitol may be a useful alternative in the treatment of ascites.