A new method for the analysis of metocurine iodide in biological fluids was developed. Metocurine iodide was quantitatively extracted with rose bengal from aqueous layer into dichloromethane layer and the amount of metocurine iodide was calculated from the amount of rose bengal which was determined by HPLC with fluorescence detector. It was possible to analyze metocurine iodide without the effect of co-prescribed drugs in the concentration range of $0.09{sim}9.10;{mu}g/ml$. The detection limits of metocurine iodide in urine and blood were 0.8 and 1.2 ng at S/N=3, each respectively.