Eighteen arterial reconstructions after trauma in the region of the knee joint were performed between 1970 and 1976. In seven cases there had been fracture of the distal femur, in five of the head of the tibia, in three dislocation of the knee joint or severe contusion of the popliteal artery. In 12 cases referral had been eight hours or later after injury. The concomitant vessel injury was not recognised in six. Vascular reconstruction by direct suture with a venous patch was performed in eight, interposition of a venous autograft in five, and saphenous vein bypass in four. Results depended upon length of ischaemia time and the level of the vascular injuries. Complete restitution to normal was achieved in only two cases, while in the remaining 12 there were defects of motor and sensory function as seen in the post-ischaemia syndrome. In four cases above-knee amputation was necessary despite successful reconstruction of the artery because there was irreversible ischaemic damage with tissue necrosis. To improve these results careful examination of blood vessels and, in questionable cases, angiography is recommended for every trauma victim.