It was previously proposed that the Arabidopsis MEI1 gene encodes a small protein with some similarity to an acrosin-trypsin inhibitor of humans [He and Mascarenhas (1998) Sex Plant Reprod 11:199-207]. Here we show that the complement strand of the MEI1 gene region encodes a predicted protein that fits better with the chromosome fragmentation phenotype of the mei1 mutant. By aligning their partial cDNA sequence with the two sources of genomic sequence available for the region, we deduced a predicted protein that contains three BRCT domains. Proteins with BRCT domains are involved in DNA repair, recombination, and cell cycle checkpoint control. This newly proposed annotation for MEI1 suggests that it might regulate the repair of DNA double-strand breaks during male meiotic recombination, which is consistent with the chromosome fragmentation defect found in early diplotene in the mei1 mutant.