A fucomannogalactan (FMG-Am) and a (1 → 3), (1 → 6)-linked β-d-glucan (βGLC-Am) were isolated from Amanita muscaria fruiting bodies. These compounds’ structures were determined using mono- and bi-dimensional NMR spectroscopy, methylation analysis, and controlled Smith degradation. FMG-Am was shown to be a heterogalactan formed by a (1 → 6)-linked α-d-galactopyranosyl main chain partially substituted at O-2 mainly by α-l-fucopyranose and a minor proportion of β-d-mannopyranose non-reducing end units. βGLC-Am was identified as a (1 → 3)-linked β-d-glucan partially substituted at O-6 by mono- and a few oligosaccharide side chains, which was confirmed after controlled Smith degradation. Both the homo- and heteropolysaccharide were evaluated for their anti-inflammatory and antinociceptive potential, and they produced potent inhibition of inflammatory pain, specifically, 91 ± 8% (30 mg kg−1) and 88 ± 7% (10 mg kg−1), respectively.