Identification of the PCR markers tightly linked to genes that encode important agronomic traits is useful for marker-assisted selection (MAS). The Cf-9 locus confers resistance to most races of the leaf mold fungus Cladosporium fulvum and belongs to a large gene family. We developed three gene-based markers (8F/10R, 8F/12R, and 10F/10R) from the Cf-9 gene sequence. Of the 101 tomato genotypes tested, 9 commercial $F_1$ hybrids carried 8F/10R-, 8F/12R-, and 10F/10R-specific bands. Our results demonstrate the usefulness of these markers for MAS for C. fulvum resistance.