Fourteen pregnant rabbits, ranging from 15 to 28 days in gestational period, were used in this experiments. The estimation of blood flow rate to the uterus was carried out by diffusion equilibrium method using antipyrine as an indicator substance. Meanwhile, the consumption rate of oxygen and glucose as well as the appearance rate of lactate and pyruvate were calculated from the blood flow rates and concentration differences between carotid artery and uterine vein. The data obtained were analysed according to the total uterine weight in order to observe any changes in the uterine blood flow and the carbolydrate metabolism at various gestational period. Results obtained were as follows: 1. The rate of uterine blood flow was high in low uterine weight and leveled off to plateau value of 15.8 cc/min./100 gm. in the uterine weight of more than 100gm., whereas the total uterine blood flow was increased persistently with the gain in uterine weight.(r=0.9374). However, the rate of increase in the total uterine blood flow was less than that of uterine weight. 5 times ncrease in uterine weight accompained 2.3 times increase in the total uterine blood flow. 2. Arterio-venous difference of oxygen content was relatively constant irrespective of uterine weight and showed the mean value of 5.7 volume %. Oxygen consumption rate was initially high at low uterine weight and droped to the minimum plateau value ranging from 15.2 to 0.71 cc/min.100gm. as in the rates of uterine blood flow. On the other hand, the total oxygen consumption rate was increased steadily with the increase in uterine weight.(r=0.8638). However, the rate of increase in oxygen consumption was less than that of uterine weight.5 time increase in uterine weight accompanied 3,1 times increase in total o2 consumption rate. 3. The glucose consumption rate was high in low uterine weight but leveled off to minimum plateau value(maximum 8.6, minimum 3.6 mg/min/100 gm) as in the blood flow rate and o2 consumption rate, whereas total glucose consumption was increased steadily with the increase in uterine weight.(r=0.948). The rate of increase in total glucose consumption was less than that of uterine weight, showing 3,7 times increase in the consumption for 5 times increase in uterine weight. 4. Lactate appearance rate per unit weight of uterus did not show significant difference at various gestational period and averaged 2.1 mg/min/100gm., ranging from 1.3 to 2.8 mg/min/100gm. Ac- cordingly the total lactate appearance was proportional to the increase in uterine weight.(r=0.953). 5. Pyruvate apperance rate showed high value in the low uterine weight and decreased promptly as the uterus gain its weight. with the findings that the rates of increase in total uterine blood flow and total consumption rate of oxygen and glucose were less than that of uterine weight, whereas the rates of increase in the total lactate appearance was similar with that of uterine weight, it is speculated that the carbohydrate metabolism in the pregnant uterus tends to be more anaerobic as gestational period proceed.