Six new complex tannins, guajavins A (5) and B (1), psidinins A (9), B (11) and C (13), and psiguavin (15), together with a variety of condensed, hydrolyzable and complex tannins, have been isolated from the bark of Psidium guajava L. (Myrtaceae). On the basis of chemical and spectroscopic evidence, the structures of guajavins and psidinins were established to consist of a (+)-gallocatechin unit and a hydrolyzable tannin moiety linked C-glycosidically, while psiguavin was found to be a novel metabolite probably derived from eugenigrandin A (7) through successive oxidation, benzylic acid-type rearrangement, decarboxylation and oxidative coupling of the gallocatechin B-ring and one of the aromatic rings in the hydrolyzable tannin moiety.