The availability of yeast glycolytic oscillator as a novel index of toxicity assay is investigated. Various chemical compounds were added to the glycolytic oscillator and the oscillation changes of NADH concentration were measured photometrically. The characteristic changes of wave patterns were observed by the additions of mercuric ion, fluoride, acetaraldehyde and so on, although respiratory inhibitors did not change the oscillation. Addition of a mixture of two chemicals causes additive or synergistic effects on the glycolytic oscillation. Further, the same oscillation can be observed even after 1 month by freeze-drying the prepared yeast extract. Although the number of chemicals which cause the characteristic oscillation changes is very limited, and the lower detection limit is not satisfactory, the possibility of a novel toxicity assay method can be shown.