A preliminary study of Cissampelos pareira Linn. from Peru yielded a new alkaloid, cissampareine. Evidence is presented for assignment to cissampareine of the empirical formula, C37H38N2O6. Cissampareine and four other bisbenzylisoquinoline alkaloids isolated from menispermaceous plants were found to show significant and reproducible inhibitory activity against human carcinoma of the nasopharynx carried in cell culture (KB). Copyright © 1965 Wiley‐Liss, Inc., A Wiley Company