We determined the concentrations of L-3-hydroxybutyrate (L-3HB) in the serum of normal and aristolochic acid (AA)-treated mice. The samples were derivatized with 4-nitro-7-piperazino-2,1,3-benzoxadiazole (NBD-PZ) and determined fluorimetrically by column-switching high-performance liquid chromatography (HPLC). Total 3-HB derivatives in serum were separated by an ODS column and then introduced to a sample loop for enantiomeric separation by two tandem CHIRALCEL OD-RH columns. The results showed that the concentration of L-3HB in the serum of normal mice was 0.81 ± 0.15 μM compared to that of AA-treated mice with 4.33 ± 2.81 μM after 3 days and 8.65 ± 2.60 μM after 5 days of AA administration (p<0.05), suggesting that serum L-3HB may be used as an indicator to determine the level of renal damage.