Summary:A 67‐year‐old man with bipolar disorder developed a Creutzfeldt‐Jakob like syndrome during lithium carbonate treatment. Lithium serum level was within the therapeutic range. Complete clinical‐electroencephalographic recovery was achieved after lithium therapy was discontinued. Several cases of lithium‐induced Creutzfeldt‐Jakob syndrome have been reported to date; all of them were elderly patients and a half had “therapeutic” lithium serum levels. Patients in this age group receiving antimanic maintenance treatment should keep lithium serum levels as low as possible. Lithium neurotoxicity should be considered in Creutzfeldt‐Jakob disease differential diagnosis, serial electroencephalograms being the most valuable.