During the search for neuraminidase inhibitors from medicinal fungi, we found that the culture broth of Phellinus linteus exhibited potent inhibitory activity. Solvent partition, Sephadex LH-20 column chromatography, and high-performance liquid chromatography (HPLC) were performed for purification of two active substances from the culture broth. According to $^1H$ NMR measurements and comparison of HPLC retention times with those of authentic compounds, their chemical structures were identified as hispidin and hypholomine B. Compounds (hispidin) 1 and 2 (hypholomine B) inhibited neuraminidase, with $IC_{50}$ values of 13.1 and 0.03 ${mu}M$, respectively.