The tertiary phenolic alkaloidal components of the rhizoma of Cocculus trilobus DC. (Menispermaceae) were examined. Two new erythrinan alkaloids, named coccutrine and dihydroerysovine, and two known erythrinan alkaloids, cocculine (V) and cocculolidine (VII), were isolated. The structures of coccutrine and dihydroerysovine were determined by spectroscopic methods as (I) and (III), respectively.