In WC-Co alloys prepared by liquid phase sintering WC grains are partly surrounded by the Co binder and are terminated by basal and prismatic facets. This work reports transmission electron microscopy (TEM) observations on basal WC/Co interfaces. Two kinds of preferred orientation relationships are found. The one most common corresponds to the joining of (0001)(WC) with (111)(Co) planes. It leads to a large parametric misfit of 15% and is observed for only small pools of Co, mainly located in corners formed by the contact between WC grains. The second type of interface corresponds to the joining of (0001)(WC) with (001)(Co) and is more rarely found. For random WC/Co orientation relationships a thin WC1-x cubic layer about two atomic rows is revealed at the interface.