In order to evaluate the cesium-induced toxic functional changes in organisms, transmembrane activities of cesium 5-sulfosalicylate (Cs(H(2)Ssal)) into human erythrocyte in vitro is presented in this paper, including kinetic characteristic of transport process and pathways involved in it. The uptake amount of Cs(H(2)Ssal) by erythrocyte was determined both by Graphite Furnace Atomic Absorption Spectrometry (GFAAS) and spectrofluorimetry. The pathways of Cs(H(2)Ssal) transporting into erythrocyte are proposed according to inhibition investigation. The influence of Cs(H(2)Ssal) on morphological properties of erythrocytes was examined using Scanning Electron Microscopy (SEM) to determined the endurable concentration extent of erythrocytes to Cs(H(2)Ssal). Results show that transmembrane of Cs(H(2)Ssal) has characteristic of first-order kinetic process during the first 2h, and four pathways were involved in its transporting activities: Ca(2+) channel, Na(+)-K(+) pump, Na(+)-Cs(+) countertransport, and anion Cl(-)/CsCO(3)(-) exchange. The transmembrane process of Cs(H(2)Ssal) can both prevent the uptake of K(+) and induces abnormal accumulation of extracellular K(+) as well as occupy some K(+)-binding sites in protein, causing some tissues losing their activities and functions. Only high concentrations of Cs(H(2)Ssal) could change morphological properties of erythrocytes greatly and cause hemolysis eventually.