The rate‐limiting enzyme in the ethylene biosynthesis pathway is 1‐aminocyclo‐propane‐1‐carboxylate (ACC) synthase. We have investigated an ozone (O3)‐induced ACC synthase gene in Arabidopsis thaliana. Four previously reported ACC synthase genes from A. thaliana (ACS1, ACS2, ACS4 and ACS5) were not induced in response to O3 stress. An O3‐induced 1 098‐bp cDNA encoding ACC synthase was isolated from foliage of A. thaliana; this sequence was identical to that of ACS6 which could be induced by multiple stimuli including touch. When plants were treated with 350 nl l−1 of O3 for 2 or 6 h. the evolution of ethylene became maximal after 1.5 h and gradually decreased thereafter. Similarly, the mRNA transcript of O3‐induced ACC synthase was detected after 30 min of exposure, attained a maximum level after 1 h, and then declined. Visible damage in O3‐treated plants was observed at the end of the 2‐h exposure. This ACC synthase gene in A. thaliana provides a useful tool for studying O3‐induced responses related to ethylene production at the molecular and genetic levels.