Thirteen phenolic compounds, 1,4-dimethoxybenzene (1), 3,4-dihydroxybenzaldehyde (2), (2E)-3-(4-hydroxy-3,5-dimethoxyphenyl)acrylaldehyde (3), 3,7-dihydroxy-4H-chromen-4-one (4), 2,3-dihydroxy-1-(3,4-dihydroxyphenyl)propan-1-one (5), 4-hydroxy-3-methoxybenzoic acid (6), 4-hydroxy-3,5-dimethoxybenzoic acid (7), methyl 3,4-dihydroxybenzoate (8), 4-hydroxy-3,5-dimethoxybenzaldehyde (9), 3,4-dihydroxybenzoic acid (10), 3-hydroxy-1-(4-hydroxy-3-methoxyphenyl)propan-1-one (11), 2,4,6-trihydroxybenzaldehyde (12) and benzene-1,2,4-triol (13) were isolated from the heartwood of Caesalpinia sappan. Their anti-inflammatory activity was evaluated against LPS-induced NO production in macrophage RAW264.7 cells. Among them, compounds 3 and 8 showed strong inhibitory activities toward the LPS-induced NO production in macrophage RAW264.7 cells with $IC_{50}$ values of 14.5 and 21.5 ${mu}M$, respectively.