We investigate the empirical effect of violence, as compared to other trade impediments, on trade flows. Our analysis is based on a panel data set with annual observations on 177 countries from 1968 to 1999, which brings together information from the Rose data set, the iterate data set for terrorist events, and data sets of external and internal conflict. We explore these data with traditional and theoretical gravity models. We calculate that, for a given country year, the presence of terrorism together with internal and external conflict is equivalent to as much as a 30% tariff on trade. This is larger than estimated tariff-equivalent costs of border and language barriers and tariff-equivalent reduction through generalized systems of preference and WTO participation.