The concentration of iodine excreted in a single specimen of urine on saliva at a given interval after the ingestion of a test dose of iodized oil has been advocated as a simple and effective screening test to determine the presence of malabsorption of fat in conditions such as cystic fibrosis of the pancreas. However, in assaying the results of this test in a group of normal children, using the original technique, the present writers encountered certain unexpected results which were investigated and are reported herein.