To explore the function of chitin in Schizosaccharomyces pombe, we have cloned chs1+ and chs2+, encoding putative chitin synthases, based on sequences in the Sanger Centre database. The synthetic lethal phenotype of the S. cerevisiae chs1 chs2 chs3 mutant was complemented by expression of S. pombe chs1+ or chs1+, indicating that both chs1+ and chs2+ in fact encode chitin synthase. The homothallic Deltachs1 strain formed abnormal asci that contained 1, 2, or 3 spores, while the Deltachs2 strain had no noticeable phenotype. The chs1 chs2 double disruptant looked similar phenotypically to the Deltachs1 strain. The Chs2-GFP fusion protein predominantly localized at the septum after the septum was formed during vegetative growth. The level of chs2+ mRNA increased just before the septum was formed. Levels of Chs2-13Myc synthesis also changed during the cell cycle. Thus, chs1+ is required for proper spore formation, and chs2+ is perhaps involved in septum formation.