In the autumn of 2003, while passing the northern part of the Broekermeer, a small polder between Amsterdam-Noord and Broek in Waterland, the author had the opportunity to inspect some fresh mud dredged from the deeper part of the canal, which runs around this polder. Four species of large bivalves were encountered: Anodonta cygnea, Anodonta anatina, Unio pictorum and Unio tumidus depressus. The last three species are new for this area and brings the total number of molluscs, which can be encountered during a walk around this polder to 52.