The potential gastroprotection of polysaccharides (SP) isolated from maté (Ilex paraguariensis) leaves of different growth stages, under different sunlight conditions and of processing methods were evaluated. The SP consist of type I arabinogalactan (AG1) containing a (1→4)-linked β-Galp chain, with substituents of arabinosyl units at O-6. This arabinogalactan seems to be attached to rhamnosyl units from a RG1, via 1→4 linkage. Oral administration of SP1, SP9, SP10, SP11 and SP12 inhibited the gastric lesions induced by ethanol in rats. Altogether, the present data indicate the therapeutic role of maté polysaccharides against gastric lesion and propose its use or of its crude plant extract as a phytotherapic medicine.