Objective To establish a method for detection of serum urocanic acid (UCA) by high performance liquid chromatography (HPLC),and explore the clinical significance of serum UCA concentration for children acute leukemia.Methods The chromatographic conditions of HPLC were set up and optimized,and the linearity of standard curve,precision,accuracy and stability were validated.Then the serum from ninety acute leukemia children and ninety non-tumor blood disease children was collected,the concentration of serum UCA was detected with HPLC,and the differences of two groups were compared to study the clinical significance of UCA in children acute leukemia.Results The HPLC method for detecting serum UCA was successfully established and optimized.The standard curves of trans-UCA and cis-UCA both showed good linearities(R2=0.999 6 and 0.999 9) at the condition of the mobile phase of acetonitrile-20 mmol/L KH2PO4,pH 3.7(5:95,V/V),flow rate of 1.2 mL/min,detection wavelength of 264 nm in HPLC.The relative standard deviation RSD％ of intra-assay and inter-assay were lower than 5％.Compared with non-tumor blood disease,the serum concentration of cis urocanic acid (cis-UCA) and trans urocanic acid (trans-UCA) of children with acute leukemia were significantly increased (P＜0.001).Compared with cis-UCA,trans-UCA was more valuable for risk classification of acute lymphoblastic leukemia (ALL).Conclusions HPLC is a good technology to titrate of UCA in serum.The concentration of serum UCA in children with acute leukemia may provide the clues for diagnosis and prognosis,with important clinical significance.