In filamentous ascomycetes, self-sterility as well as fertility depend on the mating-type (MAT) locus, whose genes code transcription factors, peptide pheromones and their corresponding receptors . Heterothallism (self-sterility) occurs between two fungal strains with compatible mating types . On the contrary, homothallism refers to a self-fertile organism with a complete sexual cycle. Heterothallic species are characterized by the presence in each isolate of only one idiomorph, either MAT1-1 or MAT1-2, while both types are present in homothallic species. Interestingly, some Stemphylium species are homothallic, others are heterothallic. Till now, the teleomorphic state of Stemphylium lycopersici has not been described. Here we report that we found the idiomorph within a collection of isolates of S. lycopersici.