Despite the identification of mutations in the methyl CpG binding protein 2 gene, the pathogenesis of Rett syndrome (RS) is still unknown. In order to clarify the role of apoptosis in this disorder, we studied lymphoblastoid cell lines in five classical RS patients and five controls, incubated with 2-deoxy-d-ribose (dRib), a reducing sugar that induces apoptosis in human cells, through oxidative damage. The apoptotic response was detected by flow cytometric analysis and agarose gel electrophoresis. The cells of RS patients showed a lower percentage of apoptosis in a routine condition than those of controls did, whereas, in the presence of dRib, the percentage of apoptotic cells in RS patients increased with time and reached the same percentage of those of controls at 72 h. The data observed here suggest that RS may have a low susceptibility or an increased resistance to the apoptotic cell death, which may be corrected only in the presence of a strong apoptotic stimulus.