Fourteen patients (11 men and 3 women) with Streptococcus bovis infective endocarditis have been observed by the Infectious Disease Section of our Department of Clinical Medicine between the years 1988-1998. The mean age was 63.2 years (range 35-85 years); 5 patients previously suffered valvular disease or had a valvular prosthesis, the infection involved the mitral valve in 6 patients, the aortic in 8, the prosthetic valve in 1. No patient developed cardiac failure or died during hospitalization; only 1 episode of major embolism (spleen) was observed. No patient required cardiac surgery. All patients became afebrile after starting antibiotic treatment; no cases of Streptococcus bovis relapse have been observed, during a six-month follow-up after antibiotics discontinuation, in 13 patients fully evaluated. The remaining patient was lost to follow-up. An underlying asymptomatic colonic neoplasm was diagnosed at colonoscopy in 7 of 11 evaluated patients. This study confirms that Streptococcus bovis infective endocarditis is relatively benign, but it stresses the frequency and potential severity of the associated colonic lesions, requiring colonoscopy and making the treatment of high risk lesion mandatory.