Abstract The electromyographic responses clicited in the first dorsal interosseus muscle by small muscle stretches or by electrical stimulation of the median nerve were investigated in parkinsonian patients and in age-matched healthy subjects. Stimuli were applied during a steady level of contraction in the intrinsic hand muscle. This ensured comparable levels of excitability in the α-motoneurone pool in patients and normals. It was found that the normal short-latency stretch reflex was almost absent in rigid patients, while responses to electrical stimulation of low-threshold nerve fibres were of equal size in both groups. This result suggests that there is a change in fusimotor control of muscle spindles in Parkinson's rigidity without alteration of the central gain of the Ia-transmitted stretch reflex.