1. D-desoxyephedrine hydrochloride was employed intravenously in an intensive study of 22 patients with psychoneurotic illness.2. It was found invaluable as a working tool for—(a) the delineation of defenses available to the patient, and the role of this delineation in diagnosis and research.(b) a nosological differentiation in so-called "border-line" syndromes.(c) the vivid clarification of transference reactions.(d) the unexpected confrontation of the alert patient with a dramatic change in his chronic symptoms, and its consequent impetus toward recovery.(e) the marked reduction in time consumed in obtaining valuable conscious and preconscious material.3. A repeated phenomenon, which we have labeled "reawakening of focal memory," has been frequently observed, and represents a challenge to the study of recall, and psychic representation.4. It allows for clearly observable phenomena even in the presence of a group, and thus affords an excellent medium for teaching purposes.