The purpose of this work was to assess the ovicidal activity of Chrysosporium merdarium, Trichoderma harzianum, Fusarium oxysporum, F. moniliforme and F. sulphureum isolated from public areas in the city of La Plata, Argentina, on Toxocara canis eggs in vitro. Each species were cultured on water agar 2% with a suspension of immature-stage T. canis eggs. At 4, 7, 14, 21 and 28 days post-culture, they were observed by light and scanning electron microscopy. One hundred eggs were evaluated and scored according to Lỳsek’s ovicidal effect classification. These procedures were repeated three times which each fungal species. Chrysosporium merdarium and F. oxysporum showed very high ovicidal activity, F. sulphureum high ovicidal activity, F. moniliforme intermediate ovicidal activity and T. harzianum did not affect the viability of T. canis eggs. Taking into account the effects on human and animal health and the environment, the species with better prospects for studying its potential use as biological control was F. sulphureum.