The light-supported component of 36CI uptake from 5 mM K'6C1 by green laminae, either chopped or vacuum-infiltrated, of Triticum aestivum L. seedlings has been determined by subtraction of dark uptake values from light uptake values and the energy sources for the uptake elucidated on the basis of the effects of 3-(3,4-dichlorophenyl)-1,1 dimethylurea (DCMU), carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP), antimycin Al (AA), and N2 on light and dark uptake.