Specific erythritol production rate by Trigonopsis variabilis increased from 0.09 to 0.19 g/g-day by varying the osmotic pressure from 1.3 to 3.9 kPa in glucose medium, but the specific growth rate decreased from 0.28 to 0.13 h(-1). Therefore, osmotic pressure was adjusted to 1.4 kPa during growth phase and to 3.7 kPa during production phase in a two-stage fermentation. Erythritol reached 46 g/l in such a system and was twice that obtained in one-stage fermentation.