Four hypotensive peptides called elapherine-A, -B, -C and -D were isolated from the body of Elaphe climacophora after removal of the internal organs. Elapherine-A, which had the lowest molecular weight, exhibited a prolonged fall for 5 min in the blood pressure of spontaneously hypertensive rats, wherase elapherin-B, -C and -D displayed a transient fall in the blood pressure. The molecular weights of elapherine-A--D estimated from sodium dodecyl sulfate (SDS) gel disk electrophoresis were 6600, 6900, 7000 and 7200, respectively. The isoelectric points of these peptides were 10.4, 10.6, 10.7 and 10.5, respectively. They possessed a single polypeptide chain of 34-35 (elapherine-A), 56-58 (elapherine-B), 56-57 (elapherine-C) and 52-53 (elapherine-D) amino acid residues.