The anti-angiogenic agent TSU-68 is known to rapidly induce cytochrome P450 activity responsible for its own hydroxylation in rats. In this study, we identified CYP1A1 and CYP1A2 as the TSU-68-induced P450 and temporally characterized the rapid induction of these isoforms. Protein and mRNA levels of CYP1A1 and CYP1A2 along with CYP1A activities were examined in rat liver after a single oral administration of 500 mg/kg TSU-68. CYP1A-mediated ethoxyresorufin O-deethylation and TSU-68 hydroxylation activities reached the maximum at 12 hr. The activities were maintained up to 24 hr and then slowly decreased down to control levels. Protein levels of both CYP1A1 and CYP1A2 were also rapidly induced with temporal profiles similar to the profile of CYP1A activity. In contrast, unlike CYP1A2 mRNA levels, which peaked at 12 hr and almost returned to control levels by 48 hr, CYP1A1 mRNA levels peaked as early as 3 hr and returned to control levels by 24 hr. Thus, CYP1A1 showed more rapid elevation and turnover of its mRNA than CYP1A2. In conclusion, TSU-68 administered to rats rapidly induced mRNA and protein of CYP1A1 and CYP1A2 as well as CYP1A activity. Furthermore, the data showed a difference in the time-dependent induction between CYP1A1 and CYP1A2 mRNAs.