Experiments were conducted with young chicks to investigate the effect of various feed ingredients on manganese (Mn) bioavailability. Crossbred chicks were fed a Mn-deficient casein-dextrose diet supplemented with corn, soybean meal (SBM), fish meal (FM), wheat bran (WB), or rice bran (RB). Although these feed ingredients contain significant quantities of Mn, dietary addition of all five ingredients consistently depressed Mn deposition in key tissues (bone, gallbladder, and pancreas) of chicks fed excess inorganic Mn (1000 mg/kg provided as MnSO4 . H2O). Corn, SBM, FM, and WB also reduced tissue Mn levels at the chick's minimal dietary Mn requirement (14 mg/kg) when fed a casein-dextrose diet. In fact, as little as 1.0% WB, 2.5% FM, and 5.0% of a corn-SBM combination were capable of markedly reducing tissue Mn concentrations. Rice bran, however, appeared to provide bioavailable Mn when added to diets containing a level of Mn at or below the chick's requirement.