Epicoccum purpurascens was evaluated as a biocontrol agent of Sclerotinia head rot of sunflower. The potential of antifungal compounds produced by E. purpurascens as fungicides was also assayed. Treatments consisted of application of E. purpurascens conidia and of partially-purified antifungal compounds produced in broth culture before inoculation with ascospores of S. sclerotiorum. Application of conidia resulted in reduced head rot incidence on greenhouse grown plants, but the application of antifungal compounds had no effect on head rot development. Capitula colonization by E. purpurascens had no negative effects on capitula development. After application of E. purpurascens to field grown plants, capitula were much less colonized than under greenhouse conditions. As a consequence, this treatment had no effect on head rot development in the field when plants were artificially inoculated with S. sclerotiorum. The search for new isolates of E. purpurascens well adapted to the fluctuating conditions typical of natural environments could contribute to achieving an acceptable level of efficacy of this organism as a biological control agent of head rot.