The international literature refers to 12 fungi and 1 virus as sunflower seed-horne pathogens, hesides 11 weakly pathogenic or saprophytic fungi. In Brazil, 22 fungi with potencial pathogenicity and 14 normally reported as saprophytes were detected; the most important are Alternaria helianthi, Scletotinia sclerotiorum, Phomopsis sp., Sclerotium rolfsii, Macrophomina phaseolina, Rhizoctonia solani, Botrytis cinerea, Verticilium sp, Botrydiodiplodia theobromae, A. zinniae, A. tenuis, Fusarium semítectum, F. solani, F. equiseti, F. moniliforme, Phoma sp., Didyrnella sp., Colletotrichum dematium, Colletotríchum sp., Cercospora sp., Corynespora sp. e Drechslera rostrata. The first two are very important due to the frequency of occurrence or to the losses they cause to the crop; Plasmopara halstedii, although not yet detected as seed-borne in Brazil, occurs under our conditions and shows potential importance. For detection and identification of seed-borne fungi, the deep-frezing method, with superficial desinfestation, is recommended. Thiabendazol (14g) + carboxin (7g) per kilogram of seed is recommended for seed treatment.