A normally fit European resident of East Africa developed a staphylococcal peri-nephric abscess following repeated episodes of furuncular myiasis caused by the tumbu fly, Cordylobia anthropophaga. A few lesions had required surgical intervention and one, presumably the source of sepsis, had become infected. There are very few descriptions in the literature of serious complications of myiasis and this is the first report of peri-nephric abscess from this source. This paper discusses the management of the myiasis and what factors determine the variation in host susceptibility and immune response to the infestation.