A histochemical study to determine the localisation of the sorbitol dehydrogenase (SoDH) during development of the chicken was performed. Kidney, liver and intestine of 7, 12 and 18 days old chicken embryos and adult chicken were used in the experiments. It was shown that the enzyme activity in kidneys is localised in the proximal convoluted tubules and in the Bowman's capsule; in the hepatic cells and in the absorption cells of the epithelium of the small intestine. The enzyme activity was localized in the cytoplasm of the cells which were stained whereas the nucleolus remained unstained. The relationship between the presence of the enzyme with the embryo cell differentiation process is postulated.