Both budding yeast Saccharomyces cerevisiae and fission yeast Schizosaccahromyces pombe have been very popular organisms used for biological research with eukaryotes for many decades. Judging from the fission yeast Schizosaccharomyces japonicus DNA sequence determined 2 years ago, this species is evolutionarily very much unrelated to the commonly used yeasts for research. Indicating evolutionary divergence, the S. japonicus makes 8-spored asci and mitosis occurs with a partial breakdown of nuclear membrane whereas the other yeasts make 4-spored asci and cells divide without nuclear breakdown. The commonly used yeast species exhibit a generation time between 1.5 and 2.0 hr, and their genetic cross takes a period of more than 7 working d. As described here, a generation time of only 63 min and meiotic analysis completed in just 2.5 d, the S. japonicus fission yeast is predicted to become a choice organism for future research on the biology of eukaryotes. 