The report provides a review of reflex modification. Reflex modification of the acoustic startle response is a technique that can provide rapid, objective and quantitative assessments of sensorimotor function. Advantages of this technique involve the ability to: test animals rapidly, test without prior training, test without utilizing invasive procedures, and provide objective, independent estimates of both sensory and motor functioning. Reflex modification techniques hold great potential for use in neurotoxicology in both the identification and the characterization of neurotoxic chemicals.