Recent progress in understanding of iatrogenic Creutzfeldt-Jakob disease (CJD) has revealed pathological and biochemical features specific to patients with iatrogenic CJD Based on the pathological and biochemical characteristics, we have identified iatrogenic CJD cases among presumed sporadic cases; in a neurosurgeon and in a patient with a medical history of neurosurgery. In addition, incidents of suspected CJD exposure via contaminated neurosurgical instruments are occasionally noted. Therefore, improvement of CJD case recognition and tracking of neurosurgical instruments are necessary to prevent iatrogenic CJD transmission via neurosurgical instruments. Further, accumulating evidence suggests that certain misfolded proteins and amyloid proteins, as well as prion proteins, are transmissible between individuals. Evaluation of the potential risks of iatrogenic transmission and the development of preventative strategies for these infectious proteins are our future tasks.