This paper studies the long- and short-run relationships between inflation and financial development. Applying the Pooled Mean Group estimator of Pesaran, Shin, and Smith (1999, Journal of the American Statistical Association 94, 621–634) to unbalanced panel data for 87 countries over the period 1960–2005, we find that a negative long-run relationship between inflation and financial development coexists with a positive short-run relationship. However, when the data are split into different income or inflation groups, these results can be observed only in low-income or low-inflation economies.