Twenty-one mental patients were given decamethonium bromide to modify electric convulsive response. A dose of 4 mg. or above was necessary to prevent aggravation of pre-existing traumatic injury. Respiratory paralysis is regularly present when doses of 4 mg. or above are given. Pentothal sodium is useful to allay fear occasioned by muscle paralysis, but in sensitive persons pentothal may produce laryngeal spasm. Training in pentothal anesthesia and oxygen administration to unconscious patients is needed by the therapist wishing to use decamethonium bromide for the more serious physical contraindications to ECT. The therapeutic effect of ECT is not interfered with by decamethonium bromide modification of the seizure. Decamethonium bromide is a powerful and potentially dangerous drug, but it is of great value when skillfully used in trained hands.