The major hemorrhagic component (HR1) in the venom of Trimeresurus flavoviridis was purified further by gel filtration on Sephadex G-200, superfine, resulting in its resolution into two parts, 1A and 1B. 1A possessed proteolytic activity towards casein, while 1B was almost free from such activity. Both components were associated with lethal toxicity. 2. The purified preparations of 1A and 1B were homogeneous as judged by several criteria. The molecular weights of the purified principles determined by dodecyl sulfate gel electrophoresis were approximately 60 000. 1A shows anomalous behaviour on ultracentrifugation and gel filtration owing to concentration-dependent polymeric interaction. The purified components were acidic glycoproteins with isoelectric points of 4.4 and they contained neutral sugar, amino sugar and sialic acid altogether amounting to 17-18% on the total weight basis. 3. The two hemorrhagic components were closely related, if not identical, immunologically.