Klippel-Trenaunay and Parkes Weber (Klippel-Trenaunay-Weber) syndromes consist of vascular malformations of the capillary, venous and lymphatic systems combined with soft tissue and bone hypertrophy of the affected extremity. Klippel-Trenaunay syndrome is a pure low-flow condition, while Parkes Weber syndrome is characterized by significant arteriovenous fistulas. The distinction of both entities is relevant, since the prognosis and therapeutic strategies differ significantly. Our purpose is to demonstrate that thick-slice dynamic magnetic resonance projection angiography (MRPA) is a non-invasive tool to detect arteriovenous shunting in Parkes Weber syndrome. Four patients underwent MR imaging and MRPA. MRPA demonstrated arteriovenous shunting in three patients. Arteriovenous shunting was characterized by early appearing draining veins. The time of arrival between normal arteries and pathological veins varied between less than 0.5 and 1.0 s. Therefore, the diagnosis in these cases could be specified as Parkes Weber syndrome. In all these cases, arteriovenous shunting was confirmed by intraarterial digital subtraction angiography. One patient showed normal results in MRPA and could be diagnosed as having Klippel-Trenaunay syndrome.