The authors report the case of a 59 year old woman with mitral valve streptococcal endocarditis complicating rheumatic valvular disease with several metastatic septic complications. In addition to ocular and cerebral localisations, the patient developed a very rare mycotic aneurysm of the splenic artery. Mitral valve replacement was necessary because of severe mitral regurgitation with major dilatation of the left heart chambers. This surgery was performed under high dose heparin therapy. Large aneurysms of the splenic artery carry a high risk of rupture. This splenic artery aneurysm was treated in the same operative session as the valvular disease by a sternolaparotomy: the aneurysm was operated first of all, and then valvular replacement was performed. Three years later, the patient is well and cured of the endocarditis. To the authors' knowledge, this is the third report of mycotic aneurysm of the splenic artery and the first case combined with surgery of the infectious valvular disease and the gastro-intestinal artery aneurysm.