The Klippel-Trénaunay syndrome is a triad of congenital anomalies characterised by haemangiomas, varicosities, and unilateral bony and soft tissue hypertrophy. Hypertrophy usually affects one distal limb, but trunk or face may be affected. Cutaneous haemangiomas (nevus flammeus) of varying extent and irregular contour are often present in the hypertrophic regions. Varicosities may also be part of the vascular lesions of the syndrome. Orofacial manifestations include facial asymmetry, jaw enlargement, and malocclusions as well as premature tooth eruption. Two cases of the Klippel-Trénaunay syndrome are presented here. Both of these show the typical hemifacial hypertrophy and premature eruption of teeth on the affected side. In the first case only the left mandibular region was affected. In contrast, in the second there was hypertrophy of the whole left side of the body including upper and lower jaws. This boy also suffers from congenital ideokinetic retardation, while the first was otherwise normal. Both cases differ from previously reported cases of the Klippel-Trénaunay syndrome in lacking any prominent facial nevus flammeus. In the first case there was also malformation of the crown of the first permanent molar on the affected side that has not been described previously.