To assess the function of the three trigeminal divisions, we studied corneal reflex, early and late blink reflexes, early and late masseter silent periods, and jaw jerk in normal subjects and in 35 patients submitted to surgery for trigeminal neuralgia. The corneal reflex was most sensitive to thermocoagulation and the jaw jerk to microcompression; the other reflexes showed an intermediate behavior, depending on afferent fiber size. Trigeminal function was less impaired after microcompression and recovered earlier than after thermocoagulation.