The aim of the research is to find out better medicinal stuff for thyroid cancer patients who are required to have a low level iodine diet. Iodine contents in 12 kinds of oriental herbal medicinal prescriptions, which are frequently used for thyroid cancer patients, are determined using instrumental neutron activation analysis. The biological certified reference material was used for analytical quality control. The relative errors and standard deviations for the iodine analysis were less than 2.88 and 18.5%, respectively. The level of iodine contents for four medicinal samples detected was in the range of about 3–210 mg/kg, the concentrations of eight samples were estimated from the detection limit under the given analytical conditions. In addition, the informative concentrations of 17 essential elements with special functions such as Al, As, Ba, Br, Ca, Cl, Cr, Fe, K, Mg, Mn, Na, Rb, Sr, Ti, V, and Zn in the samples were also determined together with their detection limits for data inter-comparison. The relative errors and standard deviations for these elements were in the range of 0.1–18.0%, and 2–20%, respectively.