Bacterial endarteritis is rare and usually affects the abdominal aorta. A case of bacterial left subclavian arteritis complicated by mycotic aneurysm is presented. An early diagnosis of infective arteritis was made based on a history of fever, sweats, rigors, and a progressive macular rash, polyarthralgia splinter haemorrhage (limited to the left arm), and a loud left subclavian bruit on admission. A mycotic aneurysm was diagnosed by computed tomography and treated surgically. In cases of endarteritis the possibility of a mycotic aneurysm should be borne in mind even when there is no evidence of endocarditis.