Sulfite, at concentrations above 1 mM and at a pH below 4, caused cell death in Saccharomyces cerevisiae X2180 as measured by the colony-forming capacity. A rapid decrease in the ATP content was observed prior to cellular death. The depletion of ATP was reversible and the lethal effect could be prevented if the cells were exposed to sulfite for periods of less than 1 h. Extent and rate of ATP depletion were dependent on time, pH value, temperature and sulfite concentrations.