During the course of recent surveys in the wheat cropping area of Buenos Aires and Entre Rios Provinces, Argentina, an unusual disease was found on wheat leaves. A fungus was isolated from the symptomatic tissues and identified as Cladosporium herbarum (Pers.:Fr) Link. Inoculations were carried out under greenhouse conditions to test pathogenicity and fulfil Koch's postulates. The symptoms of the disease and the causal agent are described.