The effect of increasing the repetition rate of click stimuli on auditory brain stem responses has been studied in young subjects with normal hearing, in old people and in patients with multiple sclerosis. The most conspicuous effects have been observed in the amplitude of the responses, especially waves II and V, and in the value of the brain stem conduction time. Increased stimulation rates may serve as a method for the assessment of the functional status of the lower auditory pathways in diverse pathological conditions.