Loss of heterozygosity at the TP53 locus occurs frequently in many types of cancer and requires polymorphic markers for detection. Several polymorphisms at the TP53 locus have been described previously, and polymerase chain reaction (PCR)-based assays have been developed to detect these polymorphisms. However, these polymorphisms have relatively low levels of heterozygosity and are often uninformative. We report here the detection of loss of heterozygosity at the TP53 locus in various human cancers by using a highly informative dinucleotide repeat polymorphism.