We investigated the role of feedback processing in decision making under risk conditions in 50 patients with amnesia in the course of alcoholic Korsakoff's syndrome (KS). Half of the patients were administered the Game of Dice Task (GDT) and the remaining 25 patients were examined with a modified version of the GDT in which no feedback was provided. Patients' results in the GDT and in the modified version were compared with that of 50 healthy subjects of whom 25 subjects performed the original GDT and 25 performed the modified version. While performance on the original GDT was superior to performance on the modified GDT in healthy subjects, KS patients performed similarly on both the GDT with and GDT without feedback. Performance on both task versions was correlated with categorization and set-shifting. The findings indicate that amnesic patients do not profit from receiving feedback for their decisions in explicit risk conditions. (Contains 4 tables and 2 figures.)