The administration of an aqueous extract made from leaves of the South American plant Solanum glaucophyllum increased active duodenal calcium absorption 6-fold in sham operated vitamin D-deficient rats and 4.5-fold in comparable animals that had been nephrectomized. These results demonstrate that the active principle from the plant does not require renal metabolism for effects on intestinal calcium absorption, a biological activity previously observed only with sterols such as 1,25-dihydroxyvitamin D3 which have a 1-alpha hydroxyl group or a steric equivalent. The similarity of action between these lipid soluble sterols and the water soluble plant material may be explained by the presence of glycosidal alkaloidal steroids in plants from the genus Solanum.