To determine the responses of plants to deficiencies of multiple metals, tobacco plants (Nicotiana tabacum L.) were subjected to treatments that were deficient in combinations of Fe and two other micronutrients, Zn and Mn. The response was measured using macro indices, including plant appearance, FW, chlorophyll concentration, and mineral concentrations, and with a molecular index, the barley (Hordeum vulgare L.) Ids2 promoter/GUS fusion gene system (Yoshihara et al. 2003, Plant Biotech 20: 33–41). Tobacco plants grown in medium with combined deficiencies grew better and had higher chlorophyll concentrations than did plants grown on medium deficient in Fe only, although the measured Fe concentrations in the plant tissues were essentially the same. The Ids2/GUS expression responded to Fe deficiency, but not to Mn or Zn deficiencies in tobacco plants when Fe was present. Tobacco plants grown in medium with combined deficiencies had clearly detectable GUS activity, but the response was significantly lower than that in tobacco plants deficient in Fe only. The Fe-deficiency symptoms were mitigated at both the visible and molecular levels. Although more precise experimental evidence is needed to explain the mitigation mechanism, the balance of minerals was shown to be an important parameter to consider when estimating iron deficiency based on tobacco plant responses.