Abstract: Twenty species of fungi were identified in moist chamber cultures of diseased organs of Helianthus annuus L. Severe infection by Botrytis cinerea Nocca & Balbis and Sclerotinia sclerotiorum (Lib.) de Bary was demonstrated, and these species together with Fusarium avenaceum (Fr.) Sacc., F. equiseti (Corda) Sacc., F. oxysporum Schlecht. and F. sambucinum Fuckel form a disease complex which is very destructive on sunflower stands in Finland. These fungi have not been reported earlier on Helianthus annuus in Finland.