Twelve patients with a clinical diagnosis of possible vascular graft infection have been studied over the last 3 years. All patients had their leucocytes labelled with indium-111 and gamma-camera imaging after 24 and 48 h. Subsequent management was according to established surgical techniques. Eight patients proved to have vascular graft infection and indium uptake was seen along the length of the graft in six. Two patients with open wound infections and synthetic grafts had localized uptake only on leucocyte scanning. Four patients, all of whom had negative scans were not thought to have infected grafts after further investigation using digital subtraction angiography and computed tomography scanning. These patients have been followed up for a median period of 19 months (range 5-25 months) and have remained symptom free. Initial experience with 111In-labelled leucocyte scanning has been encouraging, both in diagnosis and in planning the management of patients with graft infections.