Healthy or unhealthy behavior, in association with high green tea consumption, could have confounded the correlation between green tea consumption and mortality. Almost all Japanese persons consume green tea as one of their favorite beverages and it is unlikely that green tea consumption was driven by health concerns. Therefore, the possibility that the observed inverse associations between green tea and mortality were confounded by habits related to health consciousness is small. However, although we statistically controlled for a variety of potential confounding factors and conducted analysis after excluding death during the first 3 years of follow-up, and the findings were robust, we could not eliminate residual confounding. Clinical trials are ultimately necessary to confirm the protective effect of green tea on mortality.