Regreening of senescent leaves of Perilla occurs after removal of all aerial parts of the plant except for one pair of leaves. After 3 weeks' regreening, chlorophyll had increased twofold and RNA fourfold, compared with amounts present in the mature leaf. Polyacrylamide-gel electrophoresis of the rRNAs showed that although at the time of decapitation chloroplast-rRNA synthesis had ceased, this was resumed by 12 h following decapitation. The results are discussed in relation to current knowledge of the control of ribosome metabolism.