A new phthalideisoquinoline alkaloid, corytensine, has been isolated from Corydalis ochotensis Turcz., and its structure and stereochemistry have been established as (1) from spectral data and a single crystal X-ray analysis. In previous paper1, we reported the isolation and structural elucidation of several new alkaloids from Corydalis ochotensis Turcz. We now describe the structural elucidation of a further new phthalideisoquinoline alkaloid, corytensine, isolated from the whole herb of the same plant which was collected at Nan-Tou, Taiwan.