The genetic events associated with endometrial cancer are at present poorly understood. Frequent loss of heterozygosity (LOH) in a particular chromosomal region is often indicative of the involvement of a tumor suppressor gene. Previous studies are in disagreement over the involvement of a tumor suppressor gene(s) on the short arm of chromosome 3 in endometrial tumorigenesis. A set of 75 endometrial carcinomas was examined for the presence of LOH using 10 microsatellite repeat polymorphisms which are localized to chromosome 3p. In addition, these tumors were examined for the presence of replication errors (RER). Eleven of the 64 RER-negative tumors (17.2%) displayed LOH at one or more loci on chromosome 3p. The highest frequency of LOH at a single marker was 10.8% (4/37) at the locus D3S1312. The tumors investigated did not suggest that there was any common region of deletion. There was a significant increase in the frequency of 3p LOH in high-grade versus low-grade endometrioid adenocarcinomas (P < 0.05). Our results indicate that it is unlikely that a tumor suppressor gene on the short arm of chromosome 3 plays a major role in endometrial tumorigenesis.