1. Replacement therapy should be preceded by a careful pre- and post-operative personality study and prolonged observation.2. Psychotherapy alone may enhance sexual expression in castrates—as was strikingly demonstrated in a woman patient.3. In a carefully controlled situation, regular intramuscular doses of testosterone propionate definitely increased signs of sexual activity in two male castrates.4. The form which this expression took was apparently determined by the following factors: the patient's post-operative psychic make-up, the nature and handling of the transference relationship, and the nature and vicissitudes of the reality situation.5. In some cases combined psychotherapy and replacement therapy seems indicated.6. Replacement therapy under psychiatric observation stimulates dream production, which furnishes a valuable check on treatment and suggests a new approach to the study of dream symbolism.