Intramuscular pressure in the anterior tibial compartment and calf circumference were measured daily during six days following reconstructive surgery for lower limb atherosclerosis in 31 patients. Both intramuscular pressure and calf circumference were significantly increased in the operated extremity from the first postoperative day. Maximum intramuscular pressure was found on the second postoperative day. No patient developed a compartment syndrome. Calf circumference increased more slowly and reached maximum on the fifth postoperative day. Following successful reconstructive arterial surgery intramuscular pressure and calf circumference increased most in patients undergoing dissection of the groin and leg, probably reflecting intraoperative damage of lymphatic vessels. In four patients where the reconstructive arterial surgery failed intramuscular pressure and calf circumference remained unchanged postoperatively despite dissection of the groin and leg. Thus, the present study suggests that both impaired lymphatic drainage and increased capillary filtration contribute to the development of increased intramuscular pressure and calf circumference following reconstructive arterial surgery of the leg.