The synthesis of α-amylase by excised aleurone tissue can be induced by supplying either gibberellic acid (GA) or a mixture of amino acids and sucrose. Aleurone cells form RNA within 4 hours after the imbibition of water or a solution of GA. Synthesis of RNA is essential for the subsequent production of the enzyme. The primary action of GA leading to production of the enzyme begins at about the same time as the first synthesis of RNA. Loss of dormancy during after-ripening involves changes in the response of aleurone cells to gibberellin. Aleurone cells of a non-dormant domestic oat variety Torch exhibit a greater autonomy in the control of α-amylase synthesis than those of wild oats. The current hypothesis that GA acts by genetic derepression is discussed.