Little is known about extrinsic-intrinsic reflexes, especially the prototype combinative extensor hallucis response, which become apparent if proprioceptive and exteroceptive afferents of the concerning muscles are stimulated simultaneously as well as successively. With reference to this phenomenon, data from 604 patients were evaluated under neurological aspects. With the exception of the combinative reflex of the peroneal muscles, the occurrence of other combinative reflexes (of tibial posterior, anterior and extensor hallucis muscles) was of clinical relevance. All these characteristics, in the same way as Tramer's reflex and unilateral tibialis posterior reflex, correlated very well statistically with typical symptoms of an upper motor neurone syndrome. In this context the extensor hallucis combinative response is the most important one. This particular sign occurred in a systematically examined population of patients twice as often as Babinski's sign and was the single reflex anomaly in 7 per cent of 200 systematically examined cases. A double-sided manifestation, which could be seen exclusively as physiological, appeared in less than 2 per cent of 604 cases. In respect of the occurrence of combinative responses, patients belonging to different diagnostic groups, infants as well as adults, did not have statistically the same basic probability with regard to the examined neurological signs. Hence, an examination of healthy persons would not yield essential evidence. In our opinion such combinative reflexes and the other symptoms mentioned may be useful in detecting latent upper motor neuron lesion or may be helpful in doubtful cases. Whether or not the phenomenon of a combinative reflex really represents part of the latent pathognomonic flexor withdrawal reflex, cannot be decided with our clinical methods.