Analysis of the toad poison bufadienolides using the rod-thin-layer chromatography (Rod-TLC) with FID was undertaken. By the use of n-hexane/CH_2Cl_2/MeOH(11 : 8 : 1) as a developing solvent system, an effective separation of the eight bufadienolides-cinobufagin, resibufogenin, bufalin, bufotalin, desacetyl-cinobufagin, desacetyl-bufotalin, gamabufotalin and 3-oxo-cinobufagin-was obtained. Also, the reactivities of cinobufagin in oxidation and hydrolysis by using reaction mixture were checked by Rod-TLC. The contents of three major bufadienolides-resibufogenin, cinobufagin and bufalin-in the two kinds of Ch'an Su (the so-called "disk-like Ch'an Su" and "thin-plate Ch'an Su") were analyzed by the use of Rod-TLC (IATROSCAN).