Asset pricing models predict a strong connection between the real risk-free interest rate and the macroeconomy, but prior research finds little empirical support for the connection when examining expected growth. This paper documents a robust relation between the interest rate and macroeconomic uncertainty (i.e., conditional variance). Consistent with precautionary savings, high uncertainty is associated with a low interest rate using numerous data sources, time periods, and measures. A relation between habit and the interest rate disappears after including uncertainty, and the relation is stronger using long-run uncertainty. The results imply that analyses of the interest rate without uncertainty are seriously incomplete.