We follow the migration patterns of European inventors and find evidence of a novel emigration determinant: policy uncertainty. We find that policy uncertainty raises the rate of inventor emigration by a notable magnitude. With a one standard deviation in the policy uncertainty of the home country, relative to the possible destination countries, the rate of inventor emigration increases by nearly 40%. Migrating inventors are subsequently exposed to lower levels of policy uncertainty in the destination country emphasising that uncertainty motivated the move. We conclude that these effects may have strong welfare implications at the aggregate level.