Since the use of chemical antiparasitics in hen creates resistance in some parasites to them, we explored the idea of using antagonic microorganisms which may act as natural enemies with the capacity to attack, kill and phagocytose nematodes; similar to what happens with nematophagus fungi. This study aimed to shed light on the effect of fungi Verticillium dahliae and Fusarium proliferatum on the eggs of Ascaridia galli. The field work consisted on collecting intestines of backyard hens to check the feces and intestines. From the adult vermes of A. galli, eggs were removed and the different phases of embryogenesis were determined during 120 hours at 28 ºC. Thereafter, the effects of fungi V. dahliae and F. proliferatum were assessed in the development of eggs during 7 days. The bioassay with V. dahliae allowed to determine the contact phase of fungi with the egg that occurred at 24 h, the phase of adherence at 36 h, the phase of penetration at 48 h and the phase of consummation at 72 h. With the fungus F. proliferatum the same results were obtained approximately 15 h later. The results prove the ovicidal effect of the fungi studied, showing its potential in biological control of parasite eggs in the environment.