This study was conducted to predict the pharmacokinetics of oleanolic acid in humans based on animal data by allometry and several species-invariant time methods. Oleanolic acid was injected intravenously to mice, rats, rabbit and dogs (dose 1 mg/kg). The serum concentration-time profiles of oleanolic acid were best described by bi-exponential equation in all animal species. The average Cl, $V_{ss}$ and $t_{1/2}$ were 0.065 L/h, 0.019 L and 28.7 min in mice, $0.47;{pm};0.06;L/h$, $0.117;{pm};0.029;L$ and $29.7;{pm};12.2;min$ in rats, $2.77;{pm};0.88;L/h$, $1.83;{pm};0.60;L$ and $84.4;{pm};16.9;min$ in rabbits and $14.0;{pm};0.7;L/h$, $9.2;{pm};10.1;L$ and $54.5;{pm};57.2;min$ in dogs, respectively. Based on animal data, human pharmacokinetic parameters of Cl, $V_{ss}$ and $t_{1/2}$ were predicted by simple allometry. In addition, actual concentration-time profiles obtained from animals were transformed to human profiles by species-invariant times of kallynochron, apolysichron and dienetichron. The predicted human pharmacokinetic parameters of Cl, $V_{ss}$ and $t_{1/2}$ by using simple allometry and species-invariant time transformation method ranged from 48.3-97.2 L/h, 49.1-92.9 L and 45.6.187.2 min, respectively. Those predicted parameters of oleanolic acid may be useful in designing dosing schedules of oleanolic acid in future clinical studies.