Objective To study the effects of ischemic postconditioning (IP) on apoptosis in cerebral ischemia-reperfusion (I/R) injury in rats, and possible mechanisms. Methods Focal cerebral ischemia rat model was developed by cauterizing the middle cerebral artery permanently and occluding the bilateral common carotid arteries temporarily. Rats were assigned randomly into following groups: Control, Sham-operated, I/R, IP, I/R+Z-DEVD-FMK and I/R+DMSO. Apoptosis, cytochrome c (cyt-c) and caspase-3 expression were detected by immunofluorescence staining and Western blot.Results The number of TUNEL-positive cells was lower in the IP group than in the I/R group (P<0.05). Some cells were cyt-c/TUNEL double-positive in the Sham-operated, IP, and I/R groups. But not all cyt-c positive cells were TUNEL positive. Cyt-c was released in a double hump-type in the I/R and IP groups (3 hrs and 48 hrs after reperfusion). The amount of released cyt-c in the IP group was much lower 48 hrs after reperfusion than in the I/R group (P<0.05). The activity of caspase-3 increased 3 hrs after reperfusion, and peaked at 12 hrs and 24 hrs in the I/R group. The activity of caspase-3 in the IP group was lower than in the I/R group at each time point (P<0.05). The release of cyt-c in the I/R+Z-DEVD-FMK group was much less than in the I/R+DMSO group (P<0.01). The number of intact cell in ischemic penumbra in the I/R+Z-DEVD-FMK group was more than in the I/R+DMSO group (P<0.01).Conclusions IP can inhibit apoptosis of ischemic neurons after I/R. Cyt-c is involved in apoptosis of cerebral I/R injury in rats. There might be a feedback loop between cyt-c and caspase-3 in a focal cerebral ischemia rat model. IP plays a role in this loop.