Tape-record presentation of anxious bleating activates the hypophysal-adrenal system in sheep adapted to experimental conditions. Stressory reaction of the hypophysal-adrenal system is characterized by an unusually long latency (no less than 3 hours) and long duration. The pattern of the observed reaction depends on experimental conditions: in sheep that after stimulation were held in group, activation of the hypophysal-adrenal complex was much shorter than in sheep kept in pairs.