The cell cycle of Schizosaccharomyces pombe in continuous culture is controlled at two steps, one which limits the transition from G1 to S phase and the other which determines the timing of cell division. We have investigated, by means of flow-cytofluorometry, the cell cycle characteristics of nutritionally starved cells in stationary phase. Cells were shown to become arrested in either G1 or G2, in ratios which depended on the composition of the growth medium. G1 and G2 stationary phase cells share certain properties. (1) They become relatively resistant to heat shock. (2) They can reenter the cell cycle after subculture into fresh medium. (3) The G1 and G2 arrested populations have equal long-term viability in stationary phase. (4) Both populations require the activity of the cdc2+ gene for reentry into the cell cycle. We suggest that cell cycle arrest in stationary phase is regulated by the activity of the same G1 and G2 controls which limit the rate of cell cycle progression in continuous culture. The data demonstrate that in fission yeast the transition from G1 to S phase does not mark a point of commitment to the completion of the cell cycle.