Several factors have been blamed for increasing gastrointestinal absorption of aluminum. The likely role of iron metabolism was suggested some years ago. As iron and aluminum share many chemical properties, it is reasonable to think they also share biological pathways. The aim of this study was: (a) to evaluate serum aluminum transport and its relationship with iron-binding capacity, and (b) to investigate aluminum hydroxide absorption as a function of iron and aluminum. We investigated 127 patients with chronic renal failure undergoing hemodialysis in a study divided into two phases: phase 1, a basal study to investigate serum iron and aluminum status, and phase 2 in which an aluminum absorption test was performed. In phase 1, we found that the lower basal serum iron and iron transferrin saturation the greater serum aluminum (p < 0.001). In phase 2, we found a negative relationship between serum aluminum increments after the test and basal levels of serum aluminum and iron (r = -0.70; p < 0.001). These results suggest that the amount of either aluminum or iron carried by transferrin may influence the transferrin capacity to bind the other element and also may modulate, together with other factors, the gastrointestinal absorption of iron and aluminum.