Previous studies have implicated the chromosomal region at 17q25 as harboring tumor suppressor genes based on the frequent loss of heterozygosity (LOH) observed in epithelial ovarian cancers (EOC). RT-PCR validation of Affymetrix GeneChip expression of H3F3B, a member of the 3B histone family that maps to 17q25.1, revealed a doublet band in cDNA from one of four EOC cell lines, OV90. In contrast to three other EOC cell lines (TOV81D, TOV112D and TOV21G) and primary cultures derived from normal ovarian surface epithelial cells (NOSE), sequence analysis of the cDNA revealed a deletion of G at position 1484 of the transcribed sequence which is located within the 3'UTR of H3F3B. OV90 was derived from ascites fluid of an undifferentiated adenocarcinoma of ovarian origin. The variant allele was identified in 1 of 65 (2%) healthy women with no prior history of cancer and in 5 participants with ovarian tumors comprising of 4 of 79 (5%) malignant EOC, none of 10 low malignancy potential tumors, and 1 of 8 (13%) benign tumors. All carriers of the variant alleles were heterozygous and tumor samples did not exhibit preferential LOH of the normal allele. The variant allele was identified in EOC samples of clear cell (1 of 20), mucinous (1 of 8), mixed cell (1 of 3) and undifferentiated (1 of 2) histopathological subtypes but none of 34 serous or 12 endometrioid subtype tumors. One of 3 mucinous benign tumors also harbored the variant allele. The functional significance of the variant is unknown, however its presence in rare subtypes of ovarian epithelial tumors warrants further investigation.