The reported frequency of prosthetic vascular graft infections after reconstructive vascular surgery is low. However, it is a serious and potentially catastrophic complication of this treatment, with high morbidity and mortality rates. Effective therapy involves graft excision and replacement. Tc-99m HMPAO labeled leukocyte scintigraphy appears to be an accurate method of detecting prosthetic vascular graft infections. The value of leukocyte scanning is illustrated by two case reports.