Transcriptional activation of the mating-type gene mat1-Pi essential for meiosis in the fission yeast Schizosaccharomyces pombe was studied. A homozygous diploid harboring the mutation at the h+-specific sterility gene, map1, was arrested before premeiotic DNA synthesis in the nitrogen-free sporulation medium. Transcription of mat1-Pi was totally absent in the map1 mutant. The mei2 gene encoding a positive regulator for meiosis was normally transcribed in the map1 mutant, suggesting that the map1 function was specific to mat1-Pi.