Dear Editor:The relationship between colon cancer and infective endocarditis from Streptococcus bovis is a well-known entity since the first description in 1951 [1]. S. bovis, a gram-positive bacteriococcus and part of the normal bowel flora in humans and animals, accounts for 10 to 15 % of all cases of bacterial endocarditis. Large-bowel diseases and in particular colonic neoplasms have been associated with bacteremia caused by S. bovis [2]. It is, however, of utmost clinical relevance that S. bovis endocarditis may even represent the first clinical sign of otherwise asymptomatic colorectal neoplasms. Hereby, we report two cases of S. bovis-related acute endocarditis, either on a native or on a prosthetic cardiac valve, where a colonoscopy allowed early diagnosis and cure of an occult colorectal tumor.The first case refers to a 74-year-old male operated on 3 months before for combined mitral and aortic valve replacement and referred to our hospital due to repeated episodes of shiverin ...