Rats were made severely uremic with partial nephrectomy (24-hour creatinine clearance 10% of normal). Jejunal dipeptidase activities (substrates: glycyl-L-leucine, L-alanyl-L-proline, and L-methionyl-L-methionine), disaccharidase activities (maltase, sucrase, trehalase, and lactase) and morphology were studied. A highly significant increase in glycyl-L-leucine and L-methionyl-L-methionine dipeptidases was found in uremic rats compared with controls. Proline dipeptidase activities were unaltered. Disaccharidase activities showed a slight increase in sucrase in uremic rats; otherwise no change was found.