A group of 637 golden hamsters [Mesocricetus auratus] was studied and 64 of them found suffering from wet tail syndrome. They had a regional epithelial proliferation of the gut often reminding of a tumour associated with unspecified bacilliform organisms in enterocytes. Three adult females showed a similar lesion lacking of microbes with intestinal adenocarcinoma instead. Its diffuse growth reaching mesentery was combined with secondaries in mesenteric lymph nodes. Nine older hamsters showed a malignant intestinal lymphoma in similar conditions. Mutual relations of the findings were discussed. Wet tail syndrome seemed to be an intestinal precancer.