The fungal genus Verticillium harbors notorious plant pathogens that cause wilt diseases on a large variety of crops, but certain isolates or species behave as endophytes and colonize plants asymptomatically. The few known examples of soils with diseases suppressiveness to Verticillium wilt are all enriched with Verticillium tricorpus/isaacii like endophytes with biocontrol potential against pathogenic Verticillium spp. These endophytic Verticillium spp. share the same niche with pathogenic Verticillium spp. where they probably compete for place and nutrients or induce resistance responses in the plant. Not all isolates work on all crops, however, and some V. tricorpus/isaacii isolates can be pathogenic on specific crops. The challenge will be to select the right isolates and to distinguish between beneficial and potential pathogenic isolates.