Between 1986 and 1988, 38 patients (29 men and nine women), median age 65 years (range 38-85 years), underwent local intra-arterial streptokinase therapy for acute lower limb ischaemia. Three patient groups were identified: 15 with acute on chronic ischaemia (group 1), 12 postangioplasty (group 2) and 11 postfemorodistal bypass (group 3). Distal arteriographic run-off was a significant discriminant between success and failure in group 1 (n = 15, chi-2 = 11.5, P = 0.001) and in the overall group (n = 38, chi-2 = 17.2, P < 0.001). In group 2, four patients with good run-off had an unsuccessful outcome; this was due in all cases to technical problems (haemorrhage in two and intimal dissection in two). In group 3, two patients with good run-off had unsuccessful streptokinase infusions. In both cases the graft failed in the early postoperative period (< 30 days). By contrast, the four patients whose grafts occluded after 30 days had successful streptokinase infusions and long-term graft patency was achieved by further surgery and balloon dilatation. In all groups, no patient with a poor run-off had a successful outcome following streptokinase administration. The role of local intra-arterial streptokinase therapy in the critically ischaemic limb remains controversial, but these results suggest that an adequate run-off is an important factor in the selection of patients for treatment.