Several alpha-amylase clones were identified by screening a group of 345 cDNA clones derived from poly(A)+RNA from gibberellic acid (GA)-treated barley aleurone layer cells using an alpha-amylase cDNA clone that we had characterized previously as the hybridization probe. The alpha-amylase clones showed differences in the distribution of restriction enzyme sites, in the extent of cross hybridization, and in nucleotide sequence. There are at least three types of alpha-amylase clones in our collection, and the alpha-amylase cDNA clone reported by Rogers and Milliman [J. Biol. Chem. (1983) 258: 8169-8174] is a fourth type. The accumulation of alpha-amylase mRNAs in aleurones as a function of time after GA addition and of hormone concentration in the incubation medium was studied using different alpha-amylase cDNA clone probes. These studies indicate a differential control of the expression of the alpha-amylase genes by GA.