The vascular supply to the proximal tibial growth plate of the 7 weeks old chicken is described using various vascular markers. In addition the ultrastructure of metaphyseal and epiphyseal vessels as well as their supporting tissue is reported. The metaphyseal arterioles terminate in large calibre vessels which have occasional endothelial gaps and no basement membrane or supporting cells, and therefore could be classified as venous sinusoids. In contrast the epiphyseal arteriole terminates in a capillary-venule plexus lined by an attenuated and fenestrated but continuous endothelium. This paper definitively establishes that communication of epiphyseal and metaphyseal vessels across the avian growth plate does not occur. The eosinophilic streaks which often join these two vascular supplies have been described ultrastructurally and would appear to be remnants of the 'retreating' epiphyseal vessels.