Objective. Development of ascites in patients with liver cirrhosis is an ominous sign with a poor outcome. A liver transplantation must be considered, and it then becomes important to know if there are any factors indicating a worsened prognosis. Material and methods. We used official registers for a follow-up study of at least 5 years considering the prognosis of 155 prospectively recruited in-patients with cirrhotic ascites from medical units at nine Swedish university hospitals. All patients had undergone at least one diagnostic ascites tap, and had initially been questioned about background factors and physically examined according to a standardized case record form, followed by sampling of blood, urine, and ascites. Results. Death occurred within 1 year after inclusion in 53% of the cases, and was primarily liver-related in 70%. In a multivariable analysis, the two ordinary variables that showed the strongest correlation with risk of death were serum potassium and abdominal tenderness. All 22 patients with a serum potassium concentration of at least 4.8 mmol/L (maximum 5.8 mmol/L) died within 1 year after inclusion. Potassium concentration was related to renal function and potassium-saving drugs. Conclusion. This follow-up study of a prospectively recruited cohort of in-patients with cirrhotic ascites confirms their poor prognosis. Awareness of an elevated serum potassium value, which would reflect a threatened renal function, seems essential, because it may offer a simple way to identify cases with the worst prognosis. An area for further research should be to explore the significance of including serum potassium in prognostic models.