Two new bioactive indole alkaloids, 5-hydroxytryptamine (serotonin) N-4-oxobutanoic acid and 5-hydroxytryptamine N-acetyl-N-pyrrolecarboxamide, named as bufobutanoic acid (2) and bufopyramide (3), respectively, were isolated from the Chinese traditional drug Ch'an Su in addition to known bufotenine (1). The structures were elucidated on the basis of spectroscopic data. Bufobutanoic acid (2) and bufopyramide (3) exhibited cytotoxicity against murine P388 lymphocytic leukemia cells with IC50 Values of 22 mu g/mL and 7.6 mu g/mL, respectively.