Etidocaine, a new local anesthetic, was evaluated in a double-blind study using ulnar-nerve block. In addition, electromyography for the assessment of peripheral nerve motor blockade was investigated. Ten volunteers received bilateral ulnar-nerve blocks, in three series, to compare: 0.25 per cent etidocaine with 1 per cent lidocaine, each containing epinephrine 1:200,000; 0.5 per cent etidocaine with 1 percent lidocaine, each containing epinephrine 1:200,000; 0.5 per cent etidocaine with 1 percent lidocaine, both without epinephrine. The two anesthetics had similar rapid onsets of action. Etidocaine, 0.25 per cent, appeared equivalent to lidocaine 1 per cent and had approximately the same duration of action. Etidocaine, 0.5 per cent, twice the equivalent concentration, and lidocaine, 1 per cent, both with epinephrine, produced analgesia lasting 583 and 262 min, and motor block lasting 653 and 294 min, respectively. The same solutions without epinephrine provided analgesia for 320 and 165 min, and motor block for 353 and 139 min, respectively. Electromyography allowed determination of all phases of motor blockade.