The impact that added competition of imported mussels from Chile might have had on market prices is one of the main reasons given to explain the decrease in the economic performance of the mussel aquaculture sector in the European Union (EU) in the last two decades. This hypothesis has not yet been tested. In this article we test empirically for price leadership and market integration in the EU mussel market. We estimate a cointegrated vector autoregressive (CVAR) model for the French, Italian, and Spanish mussel import markets and test for price leadership. The results indicate that the import prices of Chile, Belgium, Spain, Ireland, Italy and the Netherlands are determined within a fully integrated market, so prices are proportional over time. All countries follow the lead of Chilean mussel prices in the French market, which are on average among the lowest of the main importers in this market. These results support the opinion that added competition from Chilean mussels may have contributed to the low prices in the EU market.