Oxygen consumption was determined with a closed circuit apparatus in 52 normal infants and 22 marasmatic infants. Oxygen consumption in marasmatic infants was similar to that of the normal ones when expressed in relation to the actual weight, but was significantly lower if expressed in regard to height. The lower values were observed in marasmatic infants before recovery started (Group B), while those marasmatics that had started recovery (Group A), showed intermediate values between that of the normal infants and Group B. The significance of these results has been discussed.