OBJECTIVES: Major controversy exists regarding the optimal treatment strategy in Acute Kidney Injury (AKI). The purpose of this study was to assess the incremental cost-effectiveness of continuous (CRRT) versus intermittent renal replacement therapy (IRRT) and conservative (CONS) AKI treatment in Belgium. METHODS: An area under the curve model was used, whereby patients are simulated using time-to-event data (survival analysis), combined with daily direct medical costs. Data were derived from the multi-centre SHARF4 study in which the three treatment modalities for AKI were compared. A time horizon of 2 years, starting from the admission to the hospital, was considered. Utility data were obtained from SF-36 assessment at 2 years and from literature data on in-hospital utility RESULTS: Analyses indicated that mortality rates, cost and length of stay differed significantly between treatment mode during hospitalization. The mortality rate and the cost per day during the post-discharge follow-up period showed no significant difference between the treatment modes. Utility values, which improved gradually after admission to the hospital, revealed no significant differences between the three treatment strategies. Conservative treatment was associated with a 2-year cost of €34,090 and 0.49 QALYs. The CRRT was the most expensive therapy with a cost of €51,664 leading to 0.52 QALYs. The cost and QALYs associated with IRRT were €43,711 and 0.46. The ICER of CRRT versus IRRT was €131,604/QALY, while the  ICER of CRRT versus CONS amounted to €651,318/QALY. Additionally the conservative treatment dominated IRRT. Sensitivity analysis – tornado diagram – confirmed the robustness of the results. CONCLUSIONS: This study has indicated that the most expensive treatment (CRRT) associated with an incremental cost of approximately €7952 generates only a minor increase in QALYs of 0.06 compared to IRRT. Additionally the results revealed that IRRT was dominated by CONS. From a health economic perspective conservative therapy seems to be the preferred treatment strategy.