Abstract: Objective: To estabolish a quick and sensitive method for the determination of the trace amount 3-methylhisdine（3-MH) in skeletal muscle of rats Methods: After the formation of heat and stable fluorscanmine derivatives of 3-MH in skeletal muscle of rat, high performance liquid chromatographic separation and fluorescent detection （E_X =365n m, E_m =460nm) were used to determine the 3-MH levels in the samples The solvent system is 10 mmol/L sodium phosphate（pH7.5)and acetonitrile（30%) with a flow rate of 1.0ml/min Results: No amino acid peaks but two peaks, coeluting with histidine and 3-MH, were noted when standard sample and skeletal muscle sample were chromatographed The 3-MH was eluted completely with in 5 minutes and its peak could be easily distinguished from that of histidine （separation rate＞16) The assay was linear over a range of 0.005～10.0nmol/ml （r=0.9999, P=0.0000) Conclusion: This method is not only very sensitive and accurate, but also quick and economical for determing the 3-MH amount in skeletal muscle of rats It is especially suited for analyzing samples in batches or with lower concentration of 3-MH