We have previously isolated dihydrofolate reductase (DHFR) gene from fission yeast Schizosaccharomycyes pombe by the phenotype of resistance to a folate analog, trimethoprim. One species of the DHFR transcript was identified by Northern blot analysis and was shown to be about 1,500 nucleotides in size. In order to examine regulation of the DHFR gene during cell cycle, we have analyzed the level of the DHFR mRNA in S. pombe cells in different growth phases, exponential or stationary phase, and in synchronized cells. The S. pombe DHFR mRNA level was higher in exponential phase than in stationary phase by four to five folds. The analysis of the DHFR mRNA from the synchronized cells has revealed that the level of DHFR mRNA increased by several folds on the onset of S phase, indicating that the expression of DHFR gene may be regulated at the transcriptional level during cell cycle in S. pombe as in the mammalian cells.