A series of experiments was conducted to study ribosomal RNA of aseptically germinated pea cotyledons by sucrose density gradient. A macromolecular precursor, 48S was converted to smaller molecular ribosomal RNA as the germination proceeded. The incorporation of rapidly labeled 32P was shifted to lower molecular region corresponding to sedimentation coefficient 6 through 3S. Total RNA, DNA and protein contents markedly decreased in germinating cotyledons.