The influences of acute respiratory and metabolic acid-base disturbances on the carotid, renal and coronary blood flow were measured in dogs. Respiratory acidosis was induced by artificial respiration with 8% CO2 -02 gas mixture and respiratory alkalosis was induced by hyperventilation under the control of respirator. Metabolic acidosis and metabolic alkalosis were induced by intravenous infusion of 0.3N hydrochloric acid and 0.6M sodium bicarbonate solution. To observe the effect of hyperkalemia, isotonic potassium chloride solution was infused. CVI electromagnetic flowmeter probes were placed on the left common carotid artery, left renal artery and left circumflex coronary artery. Each flow was recorded on polygraph. 1. The carotid blood flow showed rapid showed rapid and marked increase in acute respiratory acidosis. Even in the cases when arterial blood pressure was lowered during the state of respiratory acidosis, carotid blood flow increased. By the infusion of hydrochloric acid, carotid blood flow increased slowly and returned to the previous label after discontinuation of the infusion. Carotid blood flow also increased by the infusion of large amount of sodium bicarbonate, but it might be the combined effect of expansion of extracellular fluid and compensatory elevation of carbon dioxide tension. 2.The renal blood flow remained unchanged during the acute acid-base disturbances, suggesting effective autoregulation. Renal blood flow, however, increased very slowly when the infusion of potassium chloride continued for a long period. 3.Although less marked than the carotid blood flow, the coronary blood flow increased in the acute respiratory and metabolic acidosis. In asphyxiated condition, coronary blood flow increased most markedly and this might be the combined effect of hypoxia, hypercapnea, and lowering of pH. In summary, the carotid blowflow showed more marked change in the acute respiratory and metabolic acidosis than the renal and coronary blood flow. Respiratory and metabolic components of acid-base disturbances may influence the local blood flow concomitantly, there being more differences in the individual responses, but respiratory component manifested more rapid and marked effect than metabolic component.