1. The amnestic syndromes as occurring in senile psychosis, alcoholic Korsakow, after electroshock treatment, and after bilateral prefrontal lobotomy are compared both clinically and by means of psychological tests.2. Impairment of recent memory and immediate recall has been found as the type of memory impairment common to the 4 amnestic syndromes investigated.3. The theoretical implications of these findings are discussed.4. Impairment of partial memories as tested with Meyrat's method has been found only in senile psychosis.