Evidence is presented to show that the four biflavanones, GB-1, GB-1a, GB-2, and GB-2a, first isolated from the heartwoods of Garcinia buchananii Baker and G. eugeniifolia Wall, possess structures in which 4′,5,7-trihydroxyflavanone (naringenin) is linked at C-3 to the 8-(or 6-) position of the following flavanones: 3,4′,5,7-tetrahydroxyflavanone (aromadendrin), 4′,5,7-trihydroxyflavanone, 3,3′,5,7-pentahydroxyflavanone, (taxifolin), and 3′,4′,5,7-tetrahydroxyflavanone (eriodictyol). The biosynthesis of the GB biflavanones is discussed.