Congenital enlargement of one or several digits of the hands or feet, known as macrodactyly, is a rare malformation. True macrodactyly, characterized by overgrowth of all mesenchymal elements, must be differentiated from that due to tumorous enlargement of a single element, as in hemangioma, lymphangioma or enchondroma. Furthermore, macrodactyly may be isolated, but it can also be associated with several syndromes. Here we present a case of prenatally diagnosed isolated true macrodactyly of the second toe of the left foot at 24 weeks of gestation, and discuss the key points in its differential diagnosis and management. Copyright (c) 2009 ISUOG. Published by John Wiley & Sons, Ltd.