The level of certain enzymes was compared in albino, etiolated, and normal corn leaves. It was found that malic dehydrogenase and peroxidase were highest in light-grown albinos. Ribulose-1,5-diphosphate carboxylase, considered a chloroplast enzyme, was present in increasing amounts in the order albino < etiolated green < green. The level of this enzyme corresponded to the degree of chloroplast ultrastructure as determined by electron microscopic examination and insoluble protein. Only light-grown normal leaves had high catalase activity. All plants responded to light by an increased level of soluble protein, but only normal (i.e. non-albino) leaves showed an increase in insoluble protein. At least part of the higher soluble protein level could be accounted for by an electrophoretically distinct protein found only in light-grown plants.