Bioassay-guided fractionation of the $CHCl_3$-soluble fraction of a MeOH extract of the fruiting bodies of Hygrophorus russula led to the isolation of five ergosterol derivatives (1 - 5). The structures of these compounds were identified as ergosterol peroxide (1), ergosta-4,6,8(14),22-tetraen-3-one (2), ergosta-7,22-diene-3${eta}$,5${alpha}$,6${alpha}$-triol (3), ergosta-7,22-diene-3${eta}$,5${alpha}$,6${eta}$,9${alpha}$-tetraol (4), and 5${alpha}$,6${alpha}$-epoxy-ergosta-8(14),22-diene-3${eta}$,7${alpha}$-diol (5) by comparing their physicochemical and spectral data with those in the literature. These compounds were evaluated for in vitro cytotoxicity against A549 and XF498 cancer cell lines. Most of the tested compounds, except for compound 3, exhibited moderate cytotoxicity against both A549 and XF498 cell lines with $IC_{50}$ values ranging from 10.2 to 18.3 ${mu}g/ml$ and from 11.4 to 24.6 ${mu}g/ml$, respectively.