In the yeast Saccharomyces cerevisiae, ultradian oscillations of energy metabolism have been observed in continuous cultures. Here, we found that the level of the GTS1 gene product oscillated in concert with the ultradian rhythm of energy metabolism. When GTS1 was inactivated by gene disruption, the metabolic oscillation was affected severely, mostly disappearing within a day, in the absence of synchronized stress-response oscillations throughout the continuous culture. The disappearance of biological rhythms in the GTS1-deleted mutant was substantially rescued by transformation with chimera plasmids carrying GTS1 under the control of GTS1's own promoter. On the other hand, this disappearance was not rescued by constitutive expression of GTS1 under the control of the triose phosphate isomerase promoter.