The possible involvement of calcium in the regulation of H2O2-, abscisic acid (ABA)- or methyl jasmonate (MJ)-induced H2O2 generation, protein loss, and lipid peroxidation in detached rice (Oryza sativa L.) leaves was investigated. Calcium chloride and calcium ionophore A23187 effectively reduced H2O2-promoted ABA- or MJ-induced H2O2 generation, protein loss, and lipid peroxidation in detached rice leaves. It appears that ABA- or MJ-induced H2O2 generation, protein loss, and lipid peroxidation in rice leaves is mediated through blocking the entrance of calcium ions into the cytosol.