Several alkaloids from Cocculus trilobus D C. have been isolated previously. We report on the isolation and structural characterization of two Erythrina alkaloids from this plant. Coccutrine (I), a new alkaloid, was isolated as colorless needles from the phenolic fraction via silica gel chromatography and fractional crystallization (C₁₈H₂₃O₃N, m.p. 263-265°, [α] +232° (MeOH)). Its PMR, methylation product (O-methylcoccutrine, II) data suggested two methoxyl, one phenolic hydroxyl, a trisubstituted double bond, meta aromatic protons, and tetracyclic structure (lack of NH/N-methyl signals). Mass spectrum fragmentation (m/e 301, 243, etc.) indicated aromatic Erythrina skeleton. Total structure and relative stereochemistry were defined by single crystal X-ray analysis (orthorhombic, P2₁2₁2₁, a=10.69(1), b=16.65(1), c=8.80(1), Z=4; R=0.062). A second alkaloid was isolated as colorless needles (C₁₇H₂₁O₂N, m.p. 205-207°, [α] +232° (MeOH)) with PMR data resembling cocculine (III); its identity was confirmed by X-ray analysis (orthorhombic, P2₁2₁2₁, a=10.51(1), b=15.87(1), c=8.95(1), Z=4; R=0.078). From aromatic Erythrina alkaloid biosynthesis, lack of oxygenated function at C-16 in (I) and (III) is unusual—Erythrina species (Leguminosae) have C-16 oxygenation, while Cocculus species (Menispermaceae) lack it.