Brachiaria spp. is the predominate pasture grass for cattle grazing in the Orinoco watershed in Colombia. However, it has been recognized that this grass can cause liver damage, leading to photosensitization in ruminants; such injury is caused by the steroidal saponins found in this plant. Liver samples taken from five clinically-healthy bulls’ left and right liver lobes and portal vein entrance were processed by routine histological techniques to evaluate liver lesions caused by Brachiaria decumbens in cattle grazing on Colombia’s Eastern plains. The main lesions observed in these tissues were mononuclear cell cholangiohepatitis, foamy macrophages, moderate bile pigment accumulation, hepatocyte death, binucleated hepatocytes, moderate bile duct hyperplasia and multiple foci of mild fibrosis in portal areas; these were corroborated by Masson’s trichrome staining. Such lesions were predominantly distributed at the portal vein entrance, frequently being located in the periportal region. This type of lesion has usually been attributed to Brachiaria decumbens consumption, and was present in clinically healthy animals exclusively feeding on this type of grass. Thus we conclude that the tissue alterations found herein were caused by Brachiaria decumbens. This research should be expanded to involve a larger selection of cattle populations, throughout a broader geographical region.