Two new alkaloids, 4,4′-binecatorone and 10-deoxy-4,4′-binecatorone, have been isolated from fruiting bodies of Lactarius necator. The American species L. atroviridis contains 10,10′-dideoxy-4,4′-binecatorone as the main alkaloid which is responsible for the green appearance of this toadstool. © 1989.