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The methanol extract of the leaves of <em>Garcinia nervosa</em> var. <em>pubescens</em> King, which showed strong inhibitory effects on platelet-activating factor (PAF) receptor binding, was subjected to bioassay-guided isolation to obtain a new biflavonoid, II-3,I-5, II-5,II-7,I-4',II-4'-hexahydroxy-(I-3,II-8)-flavonylflavanonol together with two known flavonoids, 6-methyl-4'-methoxyflavone and acacetin. The structures of the compounds were elucidated by spectroscopic methods. The compounds were evaluated for their ability to inhibit PAF receptor binding to rabbit platelets using <sup>3</sup>H-PAF as a ligand. The biflavonoid and acacetin showed strong inhibition with IC<sub>50</sub> values of 28.0 and 20.4 µM, respectively. The results suggest that these compounds could be responsible for the strong PAF antagonistic activity of the plant.