This paper proposes a Bayesian approach to explore money-output causality within a logistic smooth transition VECM framework. Our empirical results provide substantial evidence that the postwar US money-output relationship is nonlinear, with regime changes mainly governed by the lagged inflation rates. More importantly, we obtain strong support for long-run non-causality and nonlinear Granger-causality from money to output. Furthermore, our impulse response analysis reveals that a shock to money appears to have negative accumulative impact on real output over the next fifty years, which calls for more caution when using money as a policy instrument.