We evaluated the effect of a single dose of 1.0 mg/100 g body weight of cycloheximide (CHX) on the susceptibility of hepatocytes to cell death in young (6 months old) and old (24 months old) F344 rats fed ad libitum (AL) or on dietary restriction (DR), using terminal dUTP nick end labeling (TUNEL). The proportion of TUNEL-positive hepatocytes (TPH) at baseline (without administration of CHX) was significantly higher in advanced age. However, dietary intake did not influence the proportion of TPH at baseline irrespective of age Hepatocytes cell death, detected by TUNEL, was induced in the animal by a single intravenous injection of CHX. The proportion of TPH increased with time and reached a plateau 2.5 h after the administration of CHX in young AL and DR rats and old DR rats, but continued to significantly increase 4 hours after the administration of CHX in old AL rats. Our results indicate that the death of hepatocytes at baseline and susceptibility to cell death was enhanced by CHX in hepatocytes of senile rats. Our results also suggest that dietary restriction does not suppress the enhancement of cell death at baseline, but prevents age-associated increase in the susceptibility to cell death.