Six premature infants were fed butter fat and a vitamin A preparation in an emulsified and in an unemulsified form in order to ascertain whether a reduction in particle size facilitates the absorption of these substances. The results of this investigation indicate that by reducing the particle size of fat and of an oily preparation containing vitamin A to 1 to 2 microns by an homogenizing apparatus the absorption of fat and vitamin A was greatly enhanced. Thus, the particle size of fat and of vitamin A preparations plays an important role in the absorption of these substances in premature infants.