Chronic Creutzfeldt-Jakob disease, presenting in later life, may be difficult to distinguish from other dementing illnesses. Patients with this disease may lack the characteristic myoclonus and electroencephalographic complexes. We report four patients with a slowly progressive dementia who were misdiagnosed during life and had a spongiform encephalopathy at autopsy. All four patients had early extrapyramidal rigidity, primitive reflexes, and other neurologic signs. The presence of these neurologic findings early in the course of a dementia suggests that clinicians should consider chronic Creutzfeldt-Jakob disease, evaluate the patient with electroencephalographic studies, and emphasize universal tissue precautions.