The biotransformation capacity - of the cytochrome P450 (CYP) system for example - is lower but inducibility is more pronounced in neonates than in adults. On the other hand, both enzyme activities and inducibility decline with senescence. Precision-cut rat liver slices are widely used as an in vitro tool for the examination of drug toxicity, xenobiotic metabolism or enzyme induction. The aim of the present study was to assess whether age-related changes in CYP activities and induction observed in vivo are also mirrored in vitro in liver slices. For this purpose, different CYP model reactions were measured in precision-cut liver slices from one-day-old, 40-day-old and one-year-old rats after in vitro exposure to various inducers. Similar to the in vivo situation, basal CYP activities were distinctly lower and inducibility was much more pronounced in liver slices from neonatal than in those from adult animals. Also, enzyme activities were mostly somewhat lower in liver slices from aged rats compared to those from 40-day-old rats. However, CYP inducibility was less pronounced than with younger animals too. Thus, precision-cut rat liver slices are a suitable in vitro tool for investigating age-related changes in CYP activities and induction as well as developmental differences in drug metabolism and toxicity.