The influence of increasing doses of cadmium, nickel, and tin on the net absorption of fluid as well as upon the absorption of 59Fe, administered as 59Fe-(FeSO4), from tied-off jejunal segments of male Sprague-Dawley rats were investigated. The three metals examined decreased the net absorption of fluid from the jejunal segments progressively with increasing metal doses. Cadmium was the most potent inhibitor of fluid absorption followed by tin and nickel. Tin, cadmium, and nickel diminished the absorption of 59Fe with increasing doses. The content of 59Fe of the jejunal tissue was not statistically significantly influenced by nickel, whereas tin as well as cadmium diminished the content of 59Fe significantly. Cadmium decreased the content of 59Fe to a greater extent than tin. Obviously nickel influences the rate-limiting process of iron absorption, i.e., the transfer of iron from mucosal cells into blood. Tin and cadmium appear to interact with the process of iron uptake on the surface within the mucosal cells as well as with the iron-releasing process at the contraluminal side. Cadmium as compared with tin is a stronger inhibitor for the processes involved in iron absorption.