Several different organisms cause corn(Zea mays, L.) root rot. The extent of damage to the root system varies with the aggressiveness of different causal organisms or different strains of the same causal organism. The attack of the roots by disease organisms could cause changes in the tissue analysis that would lead to misdiagnosing the cause of the problem. Studies were conducted to ascertain changes in selected mineral concentrations in the corn tissue and in plant growth resulting from various degrees of root rot caused by root infections of several different soil borne pathogenic fungi. Thermally pasteurized soil was placed in pots and infested with various fungi isolated from root lesions on corn from field studies. Corn was grown in the infested soil for four weeks in the greenhouse. Plants were harvested, roots indexed for disease, above ground visual symptoms noted, dry weight taken, and tissue analyzed for Ca, Mg, P, and K. Results showed that aerial plant parts of infected plants may exhibit typical nutrient deficiency symptoms which are not necessarily reflected in the mineral analysis of the tissue. Elemental uptake and tissue concentration appeared not to be related to changes in mineral analysis regardless of the relative soil mobility of the nutrient. Related fungi did not cause similar changes in mineral tissue concentration for the same or different minerals. Dry matter yields were reduced about 20% for each unit increase in root disease index. The use of the root disease index appears to have potential as a diagnostic tool and should be evaluated for this purpose.