The magnesium status of 22 hemodialysis patients was studied by analyses of serum, skeletal muscle and peripheral blood lymphocyte levels of magnesium. Despite elevated serum magnesium, normal magnesium levels were noted in skeletal muscle and lymphocytes. 12 patients were exposed to a low dialysate magnesium concentration, resulting in normalization of serum magnesium but no changes in muscle or lymphocyte magnesium, which might indicate slow exchange between these intracellular stores and the extracellular fluid. Normalization of serum magnesium was followed by a slight rise in circulating parathyroid hormone levels without noticeable changes in serum calcium or phosphate levels. Since signs of an absolute magnesium excess were not detected, a combination of low dialysate magnesium and the use of an oral magnesium compound as a phosphate binder might be a way to decrease aluminium exposition in hemodialysis patients.