Protein synthesis is regulated by the phosphorylation of the ␣ subunit of eukaryotic initiation factor 2 (eIF2␣) in response to different environmental stresses. One member of the eIF2␣ kinase family, hemeregulated inhibitor kinase (HRI), is activated under heme-deficient conditions and blocks protein synthesis, principally globin, in mammalian erythroid cells. We identified two HRI-related kinases from Schizosaccharomyces pombe which have full-length homology with mammalian HRI. The two HRI-related kinases, named Hri1p and Hri2p, exhibit autokinase and kinase activity specific for Ser-51 of eIF2␣, and both activities were inhibited in vitro by hemin, as previously described for mammalian HRI. Overexpression of Hri1p, Hri2p, or the human eIF2␣ kinase, double-stranded-RNA-dependent protein kinase (PKR), impeded growth of S. pombe due to elevated phosphorylation of eIF2␣. Cells from strains with deletions of the hri1 ؉ and hri2 ؉ genes, individually or in combination, exhibited a reduced growth rate when exposed to heat shock or to arsenic compounds. Measurements of in vivo phosphorylation of eIF2␣ suggest that Hri1p and Hri2p differentially phosphorylate eIF2␣ in response to these stress conditions. These results demonstrate that HRI-related enzymes are not unique to vertebrates and suggest that these eIF2␣ kinases are important participants in diverse stress response pathways in some lower eukaryotes.