In previous studies, heat shock has been reported to induce the apoptosis or programmed cell death through the activation of caspase-3. 1 investigated the effect of juniper pure essential oil on the heat shock-induced apoptosis in human astrocyte cell line CCF-STTGI. Treatment of the astrocytes with heat shock markedly induced apoptotic cell death. However, pretreatment of the astrocytes with juniper oil ingibited the heat shock-induced apoptosis. To determine whether juniper inhibits the heat shock-induced activation of these apoptotic proteases, activation of CPP32 was assessed by Western blotting. Consistent with flow cytometry. DNA fragmentation and giemsa staining, heat shock-induced activation of CPP32 was blocked by juniper oil. Poly(ADP-ribose) polymerase (PARP), cysteine protease substrates were fragmented as a consequence of apoptosis by heat shock. Juniper oil inhibited the PARP fragmentation. This juniper oil also inhibited the heat shock-induced activation of caspase-3. These results suggest that juniper oil may modulate the apoptosis through the activation of the interleukin-1-converting enzyme-like protease.