The syndrome of Visceral Larva Migrans is a zoonotic disease due to the migration in human of nematodes larval, specially ascarid. Since the larvae fail to complete their migrating cycle in humans, the diagnosis of Toxocariasis infection remains only serologic. We have been able to demonstrate by the technique of agar diffusion and the Western-blotting method that the etiology due to Toxocara canis was twice as much frequent as the one due to Toxocara cati in the syndrome of Visceral and Ocular Larva Migrans. The use of numerous antigens from adult nematodes, mainly Ascaris suum, has shown, than in France, in the syndrome of VLM at least 12% of the cases were certainly due to other nematodes. Nippostrongylus brasiliensis (or another similar nematode) of the rat might be responsible. The existence of numerous clinical and biological cases found negative in serology, allow us to suggest that some other larval nematodes, may be from wild animals, might play an etiological role.