A 87-year-old woman was admitted with a rapidly progressive confusion, disorientation and myoclonus, all suggestive of sporadic Creutzfeldt-Jakob disease (sCJD). This diagnosis was initially strongly supported by the EEG, which showed slow background activity and triphasic waves, combined with the finding of an increased level of 14-3-3 protein in the cerebrospinal fluid. Remarkably, this patient had also developed hypothermia, which, after warming-up, resulted in alleviation of the mental disturbances and disappearance of myoclonus. Over time, the EEG abnormalities disappeared. She recovered clinically for which reason the diagnosis of sCJD had to be rejected; however, she kept the inability to maintain body temperature (poikilothermia). Therefore, in patients with the aforementioned symptoms body temperature should be measured and adequately managed. Our hypothesis is that she suffered from a misleading acquired encephalopathy with reversible EEG and laboratory features, mimicking sCJD. When laboratory findings suggest sCJD it remains very important to see whether or not these findings are compatible with the clinical observations.