Hyodeoxycholic acid in Calculus Bovis Antidote tablet was determined quantitatively by dual wavelength TLC scaning. The experiment was carried out on silica gel-G plates with chloroform -ether-glacial acetic acid (2:2:1) as the mobile phase, and ethanol solution of phosphomolybdic acid (10% ) as developer, at ?s=700nm,?R= 450nm. Recovery was 103. 4% and RSD=3. 2% (n=5 ). This method is accurate and convenient It can also be used for quantitative analysis of other preparations containing hyodeoxycholic acid