A low-molecular-weight chromium-binding substance (LMWCr) has been isolated and purified from porcine kidney and porcine kidney powder and characterized. The oligopeptide is biologically active, has a molecular weight of ca 1500 daltons, and is comprised of cysteine, glycine, glutamate, aspartate, and Cr-III. Porcine kidney LMWCr is also susceptible to hydrolysis, especially under the conditions for the acid hydrolysis used in the purification of glucose tolerance factor (GTF). Combined with some similarities in the composition of GTF and LMWCr, these results suggest GTF may be an artifact resulting from hydrolysis of porcine LMWCr. (C) 1997 Elsevier Science Ltd.