Purpose : Chitin and chitosan are nontoxic natural chelators that chelate radiostrontium effectively. The purpose of this study was to compare radiostrontium chelation of chitin and chitosan with that of well known chemical chelators, namely EDTA and DTPA. Materlats and Methods : The chelaton rates of chitin, chitosan, EDTA and DTPA were compared using a column chromatography method (Sephadex G-25M, Sweden). Three kinds of chitins and four kinds of chitosans were used. All of them were water soloble. Results : Phosphated chitosan showed the highest chelation yield of more than 97% at pH 7. All of chitins, chitosans, EDTA and DTPA showed chelation yield of more than 90% independent of varing pH level. Conclusion : Chitin and chitosan have similar chelation rate as compared with EDTA and DTPA. (Korean J Nucl Med 1998;32;391-5)