The present work was carried out with the aim to evaluate the possible interference of microorganisms associated with coleoptiles on the electrophoretic patterns of isoenzymes of corn, which are used in the identification of cultivars and certification of genetic purity. Seeds of the corn cultivar C-805 were inoculated with the fungi Aspergillus flavus, Fusarium moniliforme and Penicillium spp., part treated with the misture of fungicides benlate and tecto 600 and part nontreated (T2). The seeds were left in a (BOD) incubator at 25°C and 95% of relative humidity, for thirty days. For the evaluation of physiological and health quality and of isozymatic sistems of alchool desidrogenase, malate desidrogenase, sterase, acid phosphatase, peroxidase and gluthamate-oxilacethate transaminase. Samples of seeds were taken at fifteen (1st time) and at thirty days (2nd time). For the electrophoresis a analysis control treatment (T1) was used, while wasn?t kept in chamber BOD incubator in order to solve possibles effect from chamber. The isoenzymatic sistems: alchool desidrogenase, malate desidrogenase, sterase, acid phosphatase, peroxidase and gluthamate-oxilacethate transaminase were extracted with the buffer solution Tris-HCl 0,2M pH 8,0. Seed infection by Fusarium moniliforme caused alterations in the isoenzymatic patterns of acid phosphatase, sterase, peroxidase and gluthamate-oxilacethate transaminase, from the coleoptiles whereas seed infection by Aspergillus flavus, Penicillium spp. modified only the isoenzymatic patters of esterase.