This paper describes the use of oligonucleotide probes to reveal highly polymorphic DNA regions in pomato. With a (GATA)4 probe the level of polymorphism detected is high enough to identify all 15 tomato cultivars used in this study. Individual plants of one cultivar all showed the same cultivar-specific DNA-finger-print. In an F2-population of self-fertilized cv. Sonatine, GATA-containing loci segregated in a Mendelian (3∶1) fashion. Experiments with in-vitro propagated plant material showed that the DNA-fingerprints are not affected by tissue-culture procedures. This indicates that changes in the genetic integrity, which often accompany in-vitro propagation (somaclonal variation), are not extended to the DNA detected with the (GATA)4 probe. The relative high stability and the Mendelian segregation of (GATA)4-derived DNA-fingerprints make them ideally suited for identification of tomato cultivars.