Ascorbate is one of the best natural anti-oxidant substances, and pepper (Capsicum annuum L.) has the highest ascorbate content among plants. Elicitation, wounding and other plant stress conditions are related with the oxidative burst, so we were interested in studying the putative role of pepper ascorbate oxidase (pAO) enzyme activity and its gene expression during some of these stresses. A partial pAO-cDNA was isolated by reverse transcriptase-polymerase chain reaction (RT-PCR) from pepper fruit elicited with araquidonic acid (AA). Southern blot analysis confirmed the existence of a single-copy gene encoding pAO. Northern blot analysis revealed a rapid but transient pAO-mRNA accumulation after treatment with AA, cellulase or wounding, but not with methyl jasmonate (MeJa). The pAO gene was differentially expressed from high transcription rate in roots, then stem, bud flower and almost non-expressed in leaves. AO enzyme activity levels correlated with transcript accumulation in these organs. Finally, the elicitation of pAO in response to various treatments is discussed in relation to plant defense responses.