Comparative data concerning the effects of topical anesthetics in man are not available. A technique with the use of electrical stimulation which permitted such a study was developed by the authors. The tip of the tongue is the most sensitive area in the body to this type of stimulation. Over 40 drugs with topical activity were studied with the tip of the tongue as the test site. The most potent and effective compounds are tetracaine, cocaine, dibucaine, lidocaine, and dyclonine. With the exception of dyclonine, these are toxic systemically if used in excess. The addition of vasoconstrictors, detergents, demulcents, cations, hyaluronidase, and other often suggested potentiating agents, does extend the period of activity. Need for a controlled studyNo wholly satisfactory technique has been available for studying topical anesthesia in man. Therefore, clinically significant data of a comparative nature are sparse. The efficacy of topical anesthetics is usually established by observing their ability to suppress the corneal or laryngeal reflexes. 6 , 8 The effects on the laryngeal reflex have been used as a basis for study in man. However, this technique has drawbacks because the responsiveness is variable and the reflex is obtunded after repeated stimulation. The need for a better method of study was obvious. After a num-

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