The influences of 30% stable xenon/O2 mixture on somatosensory evoked potentials were investigated in 8 patients with and without Diamox application. Changes of the amplitude of the primary cortical response occurred frequently and correlated well with the psychotropical effect of xenon. They usually normalized within 2 to 3 minutes after ending xenon inhalation. There were no significant changes of the latency of the N20.