The Chinaman’s hat shell, Calyptraea chinensis (L.) has been taken in abundance in Clew Bay and Ballynakill Harbour on the west coast of Ireland in recent years. Both of these areas were surveyed extensively in the late 19th and early 20th centuries. C. chinensis was not recorded from these areas at that time. Other records of the species from Irish waters are restricted to east and south west coasts, and date from the last century. It is suggested that the recent records result from an introduction of this species with relaid oysters which originated from the French coast.