This randomised, single-blind, placebo-controlled study involved 20 patients with chronic upper motoneuron syndrome due to ischemic cerebrovascular lesions, selected in order to ensure the greatest possible homogeneity in terms of the severity of the syndrome. All of them were treated with protirelin tartrate 4 mg/die i.m. The study included semiquantitative clinical evaluations of neurological examinations, with particular attention being paid to weakness and spasticity. These were accompanied by neurophysiological evaluations (F-waves, magnetic motor evoked potentials). Extended biohumoral investigations of possible side effects were also carried out. The results indicate a slight but statistically significant absolute improvement in spasticity and muscular strength following protirelin tartrate, especially in the lower limbs; at the same time, the drug also proved to be capable as favourably modifying the response of the biceps femoris muscle to transcranial magnetic stimulation (reappearance, increased amplitude and a reduction in the threshold of motor evoked potentials). The drug was generally well tolerated.