All available Information was gathered about the dispersion of T. infestans in Brazil and about its behavior when the species were combated with insecticides in isolated foci. Based on these elements and on what is known about factors which rule the dispersion of the invading spezies, it is debatable whether T. infestans was eliminated frorn almost all isolated foci and to have resisted two of the best conducted trials in Brazil for the erradication of the species in places situated within the area of their normal occurence. The author concludes that, in isolated foci, the action of the insecticide was added to the resistance offered to the proliferation of the species by the environmental condilion and that, because of this, the erradioatvon techniques against T. infestans should be developed in areas where the áispersion of the species is continuous.