The meiotic recombination gene rec10, which encodes a region-specific activator of recombination in Schizosaccharomyces pombe, has been cloned by genetic complementation and its nucleotide sequence determined. The rec10 gene was identified in a 5.6-kb cloned fragment by partial-deletion and insertion experiments. The nucleotide sequence of 3.5 kb of this clone revealed an open reading frame (ORF) encoding a 791 amino-acid polypeptide for the rec10 gene product. During meiosis, thermally induced in a temperature-sensitive pat1-114 mutant, the transcript of rec10 was induced to a maximal level at 2-3 h but was present at much lower levels before and after this time. The transient induction of the rec10 transcript and the rec10 mutant phenotype suggest that the rec10 gene product is involved primarily in the early steps of meiotic recombination localized to chromosome III in S. pombe.