OBJECTIVE:To establish a HPLC method for determination of Vitamin B12 in compound vitamin capsules. METHODS:Compound vitamin capsules were determined by HPLC on a ODS column at room temperature.The mobile phase consisted of methyl alcohol and 0.05mol/L KH2PO4 buffer(22∶78,pH=6.4). The flow rate was 1.0ml/min,and the detection wave length was set at 360nm.The sample size was 20?l.RESULTS:The sample size of vitamin B12 presented a good linear relationship with peak area in the range of 10.20?g～204.00?g(r=0.9 999).The average recovery was 99.7%(RSD=1.18%).CONCLUSIONS:The present method is simple,convenient,and accurate for determination of vitamin B12 in compou_nd vitamin capsules,and it also has the advantage of preventing the interference from vitamin B6 and folic acid.