Iodoalphionic acid is the contrast medium for gallbladder examination. It is rarely found in the colon and can rarely masked the gallbladder. The density of the shadow from Iodoalphionic acid was greater than that produced by iodophthalein. It was reliable peroral cholecystographic medium, which was less objectionable to take and seldom causes vomiting. Diarrhoea occurred in some cases, but not more often than with tetraiodophenolphthalein. The ingestion of Iodoalphionic acid led to low thyroidal radioiodine accumulation ranging from a few weeks to many months.