This paper studies the extent to which investor sentiment affects the Eurodollar option smile and finds that there is the dynamic interplay between sentiment-driven investors and arbitrageurs. The results reveal a significant relation between investor sentiment and interest rate volatility smile. The significant relations are stronger for put options, for short-maturity options, and for periods with higher uncertainty. The results are robust when considering controlling variables, net buying pressure, different interest rate option models, model-free method, or excluding rational components from the sentiment measures. Our findings favor the limits to arbitrage hypothesis against the positive feedback hypothesis, suggesting that the sentime...