Cathafiline and cathaformine, two novel aporphinoid alkaloids possessing a N-(methoxycarbonyl) group, along with six known alkaloids, actinodaphnine, cassythine, isoboldine, cassameridine, cassamedine and lysicamine, have been isolated and characterized from Cassytha filiformis. The structures of these compounds were elucidated by spectroscopic analyses and from chemical evidence.