Maternal perception of sound-provoked fetal movements was studied on 613 occasions in 259 risk pregnancies. The response was compared with a non-stress (N-S) test performed immediately after the sound stimulation. A positive response to sound stimulation, recorded as a fetal movement by the mother, occurred on 534 occasions (87%) and was always accompanied by a normal N-S test; sensitivity 100%. An inconclusive (3%) or negative response to sound (10%) had a specificity of 89% and a predictive value for a pathological N-S test of 19%. There was a positive correlation between inconclusive or negative test results and fetal growth retardation (P less than 0.01), fetal hypoxia (P less than 0.05) and neonatal mortality (P less than 0.05). This rapid test may have a place as a simple first-line screening test.