Of 32 patients in shock and catabolic state following shock with impaired consciousness 31 exhibited raised sodium content in their erythrocytes. On the assumption that the erythrocyte membrane acts the same as nerve cell membrane, the hypofunction of erythrocyte membrane may result in impaired consciousness. The hypofunction of erythrocyte membrane is assumed by its increased permeability in shock. A positive osmotic discrepancy between measured and calculated levels denotes altered membranous permeability.Subjectively, impaired consciousness was evaluated by clinical grading. Meanwhile, as a trial of quantification of conscious levels, we applied a new technique of analysis of power spectrum obtained by computer on the autocorrelogram of the EEG during intermittent photic stimulation. This new analytic method was useful in evaluating objective changes of cerebral function. There was a good correlation between raised sodium content in erythrocytes and depressed power spectrum. The degree of increased sodium in erythrocytes seems to correlate with patients' clinical prognosis.