Xyloglucans from seeds of Copaifera langsdorffii (XGC), Hymenaea courbaril (XGJ) and Mucuna sloanei (XGM) were obtained from milled and defatted cotyledons by aqueous extraction at 25ºC. The resulting fractions contained Glc, Xyl and Gal in a molar ratio of  2.5: 1.5: 1.0 (XGC),  3.8: 2.6: 1.0 (XGJ) and  2.5: 1.6: 1.0 (XGM). HPSEC-MALLS/RI analysis showed that all the fractions were homogeneous and that their Mw values were 1.6 X 10⁵, 2.0 X 10⁵ and 1.5 X 10⁵ g/mol, respectively. The effect of the xyloglucans on functional properties of peritoneal macrophages were evaluated, namely, O₂^·- production, NO^· production and cell-eliciting activity. They did not affect macrophage viability at the concentrations tested, when the cells were incubated for 2 hours. However, after 48 hours, XGC and XGJ gave rise to cytotoxic effects at concentrations above 100 µg/mL, as observed by a decrease in cell viability of ~40% and 30%, respectively. No cytotoxic effect was detected with the XGM xyloglucan under the assay conditions. The effects of XGC, XGJ and XGM on O₂^·- production, in the presence and absence of PMA, were not statistically significant. The three xyloglucans tested showed differences regarding the intensity of NO^· production. XGC showed a dose dependent effect, increasing NO^· production by ~ 262% and 307%, at 10 µg/mL and 50 µg/mL, respectively. However, XGJ at the concentration of 50 µg/mL,  enhanced NO^· production ~92 %. XGM did not show any significant effect on NO^· production. The cell eliciting activity was assayed by treating the mice with 100 and  200 mg/Kg of XGC, XGJ and XGM.  The number of peritoneal cells increased by ~146% and 388%, 24 h after inoculation with  XGC (100 and  200 mg/Kg, respectively). At the concentration of 200 mg/Kg of XGJ, that of recruited cells reached ~576% when compared with the control group, while XGM at the same concentration increased the number of cells by ~207%. The results indicate that xyloglucans from C. langsdorffii, H. courbaril and M. sloanei exhibit immunomodulatory activity.  In spite of similar structures of the polysaccharides tested,  different responses were observed, probably due to specific features in their fine structures. Supported by CAPES, CNPq and PRONEX.