An analysis was made of response latencies of four young-adult, audiometric-test-sophisticated Rhesus monkeys to near-threshold two-kilocycle stimulus tones. The animals were restrained during the test, and headphones were used to deliver the tone. Equal log unit decreases in stimulus intensity produced a positively accelerated response latency curve for the group. Variances tended to increase logarithmically with a decrease in stimulus intensity, though variability was consistent throughout the ten days of testing within each intensity level. Latency measurements provide an objective indication of 'goodness of performance' during sensory threshold testing of animals.