Abstract: A method using high-performance liquid chromatography (HPLC) with fluorescence detection was presented for the simultaneous measurement of the eprinomectin, avermectin, doramectin and ivermectin in liver. Samples were extracted with acetonitrile and cleaned up using solid phase extraction on alumina-B and C₁₈ column, and followed by derivatization with acetic anhydride and 1-methylimidazole in acetonitrile. The optimum time required for the completion of derivation reaction of the 4 drugs was 100 min at 96℃. Mean recoveries of the 4 drugs in bovine liver ranged from 70.02% to 88.75%. The intra-and inter-day variations were less than 8.52% and 7.13% respectively. The limit of detection was 0.4-0.5 μg/kg, and the limit of quantitation of the method was 2 μg/kg for all of the 4 drugs. The procedure provides a reliable and sensitive method for routine residual analysis.