Comparative changes in protein, free amino and keto acids have been studied in different seedling parts ofCyamopsis tetragonolobus plants in light and dark. Endosperm recorded higher level of free amino acids in darkness than in light, while a low concentration of protein was exhibited both, in light and dark. The breakdown of soluble protein was more in darkened cotyledon due to higher protease activity. The large increase in the free amino acids in the hypocotyl during seedling growth in the dark may be due to its restricted capacity to incorporate all the amino acids into proteins. Root samples from light recorded higher soluble protein as well as a higher free amino acid pool. α-Oxoglutaric acid (α-oga) was recorded in low levels and at few growth stages in both light and dark. In light raised cotyledon samples, the dominating keto acids are phosphoenolpyruvate and pyruvic acid. Low levels of oxaloacetate in light, like α-oga, indicate its rapid utilization during growth, but its accumulation in the dark may suggest sluggish protein synthesis thus sparing the utilization towards the synthesis of amino acids. Utilization of asparagine and glutamine was also affected in dark.