Ten per cent of citrate and citrated blood were injected on 22 dogs and on 14 dogs, respectively. Results obtained are as follows: 1) In the cases infused citrate, no fatal cases were observed inspite of severe intoxication when infusion rate was less than 0.45g (100cc)/Kg in an hour, though, no marked intoxication was seen when the rate was less than 0.23g (50cc)/Kg in half an hour. (cc: volume converted into blood) 2) In the cases injected citrated blood, no fatal cases were observed inspite of severe intoxication when injection rate was less than 0.35g (60cc)/Kg in an hour, though, no marked intoxication was seen when the rate was less than 0.09g (20cc)/Kg in half an hour. (g: citric acid volume, cc: injected blood) 3) It was thought that the difference in 1) and 2) was caused by weakening of body's defense mechanism for citric acid due to the influence of blood transfusion, or by another factor, that is, mainly the influence of circulatory overloading. 4) A typical symptom of citric acid intoxication was fibrillary twitching of muscle. 5) The influence of citric acid was disappeared within 2 to 3 hours; death due to citric acid intoxication was never seen 2 to 3 hours after injection.