In this study, we attempted to identify apoptotic Syrian hamster embryo (SHE) cells by detecting the specific cleavage of poly(ADP-ribose)polymerase (PARP). Apoptosis was unequivocally identified in serum-deprived SHE cells. After protein electrophoresis and transfer, the anti-PARP antibody (C-2-10) was applied in order to visualize PARP degradation and the anti-polymer antibody (LP96-10) was used to identify PARP and its expected 89-kDa fragment on the membrane after renaturation and NAD+ addition. Results showed that PARP rapidly disappeared during apoptosis in SHE cells, but the resulting fragment remained undetectable with the anti-PARP antibody and no stable polymerase activity of this fragment was measured using anti-polymer antibody. Serum-starved SHE cells were compared to the etoposide-treated HL60 cell line as a control for typical apoptosis-related PARP cleavage. These results underline the fact that while PARP degradation is a criterion for apoptosis, the diagnosis of apoptosis can not rely exclusively on the appearance of its 89-kDa fragment as this signal may fail to appear in some cell systems.