Fulminant Wilson's disease (WD) is almost invariably fatal, and liver transplantation is the only life-saving treatment. Decompensated chronic WD usually responds to chelation therapy. Our aim was to validate 3 published scoring systems for deciding between chelation treatment and liver transplantation in patients with chronic decompensated and fulminant WD. Model for end-stage liver disease (MELD) score, as well as WD prognostic index (WPI) and its recently revised version (RWPI) were evaluated as predictors of the safety for chelation therapy. A group of 14 adult patients with decompensated chronic WD who improved on penicillamine treatment were compared with 21 patients with fulminant WD. The diagnosis of WD was based on increased urinary copper excretion and confirmed by elevated liver copper content and/or mutation analysis of the WD gene. The MELD score, WPI, and RWPI were calculated for all patients with WD. The accuracy of the MELD score, WPI, and RWPI for prediction of response to chelation therapy in patients with decompensated chronic WD was 0.968, 0.980, and 0.993, respectively. None of the decompensated chronic WD patients had a MELD score >30, RWPI >11, or WPI >7. RWPI showed the highest accuracy and the lowest false negativity compared with WPI and MELD. In conclusion, our data indicate that RWPI, originally proposed for pediatric patients, is also useful for adults.