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Detailed analysis of the subjective sensations of 135 healthy subjects during 20- to -30 min voluntary hyperventilation was performed. The hyperventilation levels (V EI = 20 l/min, V EII = 30 l/min, V EIII = 40 l/min) were chosen so that manifestations of paroxysms of hyperventilation syndrome (HVS) of different severity were simulated. Regular features in the time course of development of HVS symptoms were revealed: (1) specific peripheral subjective sensations and symptoms changed consistently, being peculiar sensory equivalents (correlates) of hyperventilation-related changes in gaseous metabolism and acid-base balance; (2) sensations and symptoms of central origin developed in waves, with considerable individual variations in manifestation and emotional hue and were closely correlated with changes in systemic hemodynamics and brain circulation disorders.