The fission yeast Schizosaccharomyces pombe has no large vacuoles under normal growth conditions, although budding yeasts usually have large central vacuoles. The minimum inhibitory concentration of amphotericin B to S. pombe was 0.5 microgram ml-1; treatment with 0.2 microgram ml-1 for 20 min induced rapid and extensive vacuolation in S. pombe exponential phase cells. Growth rate of the cells with 0.2 microgram ml-1 amphotericin B was much reduced for 6 h, showing extensive vacuolation. Vacuolation in itself was not fatal: on removal of the drug, most cells recovered gradually and eventually multiplied.