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Edible mycorrhizal mushrooms are 1ich in several bioactive compounds responsible for their interesting health benefits (1). Polysaccharides, terpenoids and phenolic compounds have been indicated as the most important contributors to the anti-inflanunatory activity of mushroom species (2). In the present study, ethanolic extracts of seven mycorrhizal mushrooms were obtained by maceration and chemically characterized in terms of phenolic acids by HPLC-DAD. The extracts, the identified phenolic acids and also synthesized methylated and glucoronated derivatives of those acids were studied regarding anti-inflammatory activity evaluated through inhibition of nitric oxide (NO) in LPS (lipopolysaccharide) activated RAW 264.7 macrophages. Among the studied mushrooms, Boletus impolitus presented the highest amount of phenolic acids (675± 23 μg/g), due to the high contribution of cinnamic acid(505 ±12 μg/g), and also displayed the highest NO production inhibition (ECso=166 ± 10 μg/mL). The phenolic acids content in the different species was as follows: B. impolitus >C. cibarius>A. caesaria>L. deliciosus>B. aereus>M. esculenta>B. edulis, while the NO production inhibition ECso values were in the order:B. impolitus >A. caesaria>C. cibariu.s>L. deliciosus>M esculenta>B. aereus>B. edulis. Among the individual compounds, cinnamic acid (CA) showed the highest activity(EC50= 182 ± 16 μM), followed byp-hydroxybenzoicacid (HA; 239 ± 29 μM)and p -cotunaiic acid (CoA; 442± 33 μM), which highlights the conhibution of citmamic acid for the anti-inflammatory potential displayed by mushrooms. Comparing the NO production inhibition activity of the parent phenolic acids and their conjugated derivatives (G-glucuronated, M-methylated), the order was as follows: p -hydroxybenzoic acid: HA> HA-M3 > HA-M2 > HA-M1 > HA-G; p-coumaric acid: CoA-M1 > CoA-G> CoA-M2 > CoA-M3 > CoA and cinnamic acid: CA-G > CA> CA-M. The results in the present study show the contribution of phenolic acids to the anti-inflammatory activity of mushrooms and also demonstrated that conjugation reactions can influence the bioactivity of the phenolic acids.