Iron absorption in dogs without pancreatic secretion was studied measuring the percentage of radioactivity retained in red cells. Two groups were treated con 59Fe (5 microCi), given in the stomach: one group control and other undergoing pancreatic duct ligation. Increased absorption was observed in the last group. The influence of secretion on iron absorption, after administration of 60 mg of Fe (as ferrous sulphate solution pH 4.5), was also studied in three groups of dogs, treated with 18 Clinical Units of secretin. In one group, the pancreatic secretion was extracted from intestine by putting a catheter in the pancreatic duct. In the other two, the pancreatic duct remained normal, one with and other without the iron dose (control). A possible inhibitory effect of secretin on iron absorption was observed. Plasma Iron values remained without changes one hour after the iron administration, as well as TIBC, % saturation and transferrin values.