The toxic effects of Ipomoea carnea subsp. fistulosa were evaluated in guinea pigs by administration of dry leaves during 45 days. Swainsonine and calystegines B 1 , B 2 and C 1 were isolated and quantified. Clinical signs included emaciated and loss of body weight. Histological evaluation demonstrates numerous vacuoles in the cytoplasm of pancreas, liver and renal cells. Vacuolation was also evident in neurons of brain stem, mainly pontine nuclei. Neuronal lectin binding pattern showed a strong positive reaction to Con-A (Concanavalia ensiformis), WGA (Triticum vulgaris), sWGA (succinylated T. vulgaris) and LCA (Lens culinary). This result is coincident with the lectin histochemistry staining pattern of the vacuoles described in CNS of ruminants. We conclude that I. carnea subsp. fistulosa induces an intralysosomal accumulation of mannose-containing oligosaccharides in guinea pigs, which makes it a valuable animal model for the reproduction of induced α-mannosidosis.