Clinico‐pathological phenotypes of patients with prion diseases were compared with their PrP genotyes and transmission rate to mice. Sporadic and iatrogenic CJD patients without mutation and familial CJD patients with E200K showed uniform clinico‐pathological features, synaptic‐type deposition of PrPCJDand high rate of transmission of the disease to mice. GSS patients with P102L showed long duration of ataxia, numerous plaques in cerebellar cortex and transmitted the disease to mice in only one third of inoculated cases. Other mutations such as P105L, A117V, Y145stop, V180I, M232R and various insertions have particular phenotypes, distinct distribution patterns of PrPCJD, and untransmitted or inconclusive transmission to mice. Polymorphism at codon 129 may modify the phenotypes and transmission rate to mice. Therefore, prion diseases have a wide range from infectious disease to non‐infectious, hereditary metabolic