Abstract: Ricin was purified from Ricinus communis beans to apparent homogeneity by ammonium sulfate precipitation, Sepharose-4B affinity chromatography, and followed by molecular sieve chromatography. The purified preparation showed two protein bands with relative molecular weights of 32 kDa and 34kDa when subjected to sodium dodecyl sulfate-polyacrylamide gel eloctrophoresis. The isoelectric point of the purified Ricin was pI6.1 and pI6.7 determined by isoelectric focusing (IEF). There were five peaks when Ricin was subjected to high performance liquid chromatography (HPLC) under non-denaturing conditions, indicating this Ricin consisted of five different multimers. Purified Ricin revealed high toxicity to mouse, but had no any toxicity to Prodenia litura Fabricius larvae.