The apolar fraction of the crude alcoholic extract of the sponge Euryspongia n. sp. was shown to display anti-inflammatory activity. Bioassay guided chromatographic purification led to the isolation of a known compound petrosterol (1) of 3beta-hydroxy-24-norchol-5-en-23-oic acid (2), which has never yet been found as a natural substance, and of a new steroid, 3beta-hydroxy-26-norcampest-5-en-25-oic acid (3). The absolute configurations of 2 and 3 were deduced from comparative 1H NMR data of the (S)- and (R)-phenylglycine methyl ester derivatives. These compounds were evaluated for their anti-inflammatory activity against 6-keto-prostaglandinF1alpha release in a human keratinocyte cell line HaCaT.